JP2008153135A - Anode current collector for dry cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an anode current collector for a dry cell which can reduce material cost for manufacturing a dry cell and can prevent a current collecting efficiency from being lowered due to a reduction of a surface area as well. <P>SOLUTION: The anode current collector is provided with a column-like shaft portion, a head portion of a large diameter circular plate arranged near a base end of the shaft portion and a top end portion of an approximately conical shape arranged on a top end of the shaft portion. As to the shaft portion, a whole or a part of the shaft portion on a side of the head portion in a lengthwise direction excepting a predetermined area is made to be smaller in a diameter than the predetermined area and on a surface of the smaller diameter portion, there are formed concave portions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a negative electrode current collector for a dry battery that is incorporated in an axial center portion of the dry battery.

  In general, a shaft portion of an alkaline battery or a nickel battery has a cylindrical shaft portion (11) as shown in FIG. 10 and a large-diameter disk-shaped head portion provided near the base end of the shaft portion. The negative electrode collector (1) comprised from (12) and the truncated cone-shaped front-end | tip part (13) provided in the front-end | tip of an axial part is integrated.

As one method for reducing the manufacturing cost of such a dry battery, a method for reducing the material cost of the negative electrode current collector has been proposed.
In the following Patent Document 1, as a technique for reducing the material cost of the negative electrode current collector, the root portion that fits into the through hole of the sealing cap of the negative electrode current collector has a larger diameter, and the other portion has a diameter larger than the root portion. A technique for reducing the size is disclosed.

  However, in the disclosed technique of Patent Document 1, although the material cost can be reduced, the surface area of the negative electrode current collector is reduced, and the contact area with the gelled negative electrode is reduced. The problem that it ends up occurs.

On the other hand, Patent Document 2 below discloses an anode current collecting rod for a dry battery having a surface with irregularities.
However, the technology disclosed in Patent Document 2 is a method in which the surface is subjected to uneven processing in order to improve the adhesion between the anode current collector rod and the anode mixture. It did not contribute at all.

Microfilm of Japanese Utility Model No. 50-23682 (Japanese Utility Model Publication No. 51-104320) JP 58-40778

  The present invention has been made to solve the above-described problems of the prior art, and can reduce the material cost when manufacturing the dry battery, and the surface area can be reduced to reduce the current collection efficiency. There is no negative electrode current collector for a dry battery.

  The invention according to claim 1 includes a cylindrical shaft portion, a large-diameter disk-shaped head portion provided near the proximal end of the shaft portion, and a substantially conical tip portion provided at the tip of the shaft portion. The shaft portion is configured such that the whole or a part of the length direction excluding the certain range on the head side is smaller in diameter than the certain range portion, and the small diameter portion The present invention relates to a negative electrode current collector for a dry battery, wherein a concave portion is formed on the surface of the battery.

  According to a second aspect of the present invention, there is provided a cylindrical shaft portion, a large-diameter disk-shaped head portion provided in the vicinity of the proximal end of the shaft portion, and a substantially conical tip portion provided at the distal end of the shaft portion. The shaft portion has a recess formed on the entire surface or a part of the length direction excluding a certain range on the head side, and the length of the recess is The present invention relates to a negative electrode current collector for a dry battery, characterized in that it is shortened by a length corresponding to the surface area increased by the formation of the recess compared with the length when not formed.

  The invention according to claim 3 relates to the negative electrode current collector for a dry battery according to claim 1, wherein the recess is formed by rolling.

  The invention according to claim 4 relates to the negative electrode current collector for a dry battery according to claim 3, wherein the rolling process is a knurling process.

  According to a fifth aspect of the present invention, in the portion of the shaft portion where the concave portion is formed, the surface of the portion excluding the concave portion as the concave portion is a smooth surface. It relates to the negative electrode collector for dry batteries as described in any one of.

  The invention according to claim 5 relates to the negative electrode current collector for a dry battery according to any one of claims 1 to 4, wherein electroplating or electroless plating is performed.

According to the first aspect of the present invention, all or part of the shaft portion in the length direction is a small-diameter portion, and the concave portion is formed on the surface of the small-diameter portion. The volume can be reduced, and the material cost can be reduced without causing a decrease in current collection efficiency due to a decrease in contact area with the gelled negative electrode.
In addition, since a certain range on the head side of the shaft portion, which is a portion that comes into contact with the sealing cap and the gasket when assembled as a dry battery, is not small in diameter and no recess is formed, the gel-like negative electrode Leakage is prevented from occurring.

According to the invention of claim 2, the concave portion is formed on the whole surface or a part of the surface in the length direction excluding a certain range on the head side, and the length is increased by the formation of the concave portion. Since the length corresponding to the surface area is shorter than the length when the concave portion is not formed, the volume of the material can be reduced without reducing the surface area, and the contact area with the gelled negative electrode It is possible to reduce the material cost without causing a decrease in the current collection efficiency due to the decrease in.
In addition, since a concave portion is not formed in a certain range on the head side of the shaft portion, which is a portion that comes into contact with the sealing cap and the gasket when assembled as a dry battery, leakage of the gelled negative electrode is prevented. The

  According to the invention which concerns on Claim 3, work hardening generate | occur | produces in a axial part and a product intensity | strength can be improved by forming a recessed part by a rolling process.

  According to the invention which concerns on Claim 4, since a rolling process is a knurling process, many recessed parts can be easily formed in the axial part surface.

  According to the invention which concerns on Claim 5, in the part in which the recessed part of the axial part was formed, since the surface of the part except the part dented as a recessed part is made into the smooth surface, a gasket is damaged when incorporating in a dry cell It is prevented.

  According to the invention which concerns on Claim 6, by carrying out electrolytic plating or electroless plating, the metal fine piece which dig into the raw material surface and surface of a collector can be coat | covered by plating, and it incorporates in a dry battery. It is possible to prevent generation of hydrogen gas at the time.

Hereinafter, preferred embodiments of a negative electrode current collector for a dry battery according to the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing a first embodiment of a negative electrode current collector for a dry battery according to the present invention, in which (a) shows a state before concave processing or uneven processing described later, and (b) shows a completed state, respectively. ing.
The negative electrode current collector (1) according to the first embodiment includes a cylindrical shaft portion (11) and a large-diameter disk-shaped head portion (12) provided near the base end of the shaft portion (11). And a substantially conical tip portion (13) provided at the tip of the shaft portion (11).

  The shaft portion (11) has a diameter (D) of the whole length or a part (the whole case is shown in the illustrated example) excluding the certain range (11a) on the head (12) side. The diameter is smaller than the diameter (d) of the portion of the certain range (11a), and a recess is formed in the small diameter portion (11b).

The fixed range (11a) on the head (12) side of the shaft portion (11) is the same range as or longer than the portion in contact with the sealing cap and the gasket when the current collector (1) is incorporated in a dry battery. It is said.
This is to prevent the occurrence of leakage of the gelled negative electrode by not forming the concave portion in the portion in contact with the sealing cap and the gasket.

The concave portion on the surface of the small diameter portion (11b) can be formed by one of the following two processing methods.
The first method is a processing method (hereinafter referred to as concave processing) in which a part of the material such as grooving is removed to form only a concave portion on the surface before processing (see FIG. 1A). It is.
The second method is to form both concave and raised protrusions on the surface before processing (see FIG. 1 (a)) by applying pressure to the material such as rolling to deform it. This is a method (hereinafter referred to as uneven processing).

In this invention, it is preferable to form the recessed part of the surface of a small diameter part (11b) by the 2nd method, specifically, a rolling process.
This is because by forming the concave portion by rolling, work hardening occurs in the shaft portion, and the product strength can be improved.

  FIG. 1B shows an example in which oblique lattice-shaped recesses are formed by knurling the surface of the small diameter portion 11 b in the state of FIG. By performing knurling, a large number of recesses can be formed regularly and simply.

The shape of the recess is not limited to that shown in FIG. 1B, and other shapes can also be adopted.
2A to 2D are diagrams showing examples of other shapes of the recesses. 2A to 2C show a partial front view of the shaft portion 11, and FIG. 2D shows a partial front view and a cross-sectional view.

In the example of FIGS. 2 (a) and 2 (b), a plurality of annular recesses extending in the circumferential direction are formed on the surface of the small-diameter portion (11b) in parallel at regular intervals in the length direction. ) Has a V-shaped cross section of the annular recess, and FIG. 2B has a concave section of the annular recess.
In the example of FIG. 2C, a spirally extending groove is formed on the surface of the small-diameter portion (11b).
In the example of FIG. 2D, a plurality of concave stripes extending in the length direction are formed on the surface of the small diameter portion (11b) at regular intervals in the circumferential direction.
The concave portions shown in FIGS. 2A to 2D may be formed by concave processing or may be formed by concave and convex processing.

FIG. 3 is a view showing a second embodiment of the negative electrode current collector for a dry battery according to the present invention, wherein (a) is a front view and (b) is a cross-sectional view taken along the line AA. (C) is a reference diagram for length comparison.
The negative electrode current collector (1) according to the second embodiment also has a cylindrical shaft portion (11) and a large-diameter disk-shaped head portion (12) provided near the base end of the shaft portion (11). And a substantially conical tip portion (13) provided at the tip of the shaft portion (11).

  The shaft portion (11) has a concave portion formed on the entire surface or a part of the length direction excluding the certain range (11a) on the head (12) side (the whole case is shown in the illustrated example). Has been. Hereinafter, the part in which this recessed part was formed is called a process part (11c).

Furthermore, the length of the shaft portion (11) is equal to the length (L1) corresponding to the surface area increased by the formation of the recess compared to the length when the recess is not formed (see FIG. 3C). It has been shortened. That is, while the surface area is increased by forming the recess, the length is shortened by an amount corresponding to the surface area.
More specifically, the surface area per unit length increased by the formation of the recess is ΔS, the surface area per unit length of the certain range (11a) is S1, and the length of the portion where the recess is formed is L2. The shortened length L1 = ΔS × L2 / S1.

The fixed range (11a) on the head (12) side is the same as or longer than the portion in contact with the sealing cap and gasket when the current collector (1) is incorporated in a dry battery.
This is to prevent the leakage of the gelled negative electrode as in the first embodiment.

On the surface of the processed portion (11c), a recess is formed over the entire length.
The concave portion is formed by the above-described concave processing, that is, a processing method of removing only a concave portion with respect to the surface before processing by removing a part of the material such as grooving.
In the illustrated example, the recess is formed with a plurality of recesses extending in the length direction at regular intervals in the circumferential direction. However, the shape of the recess is not limited to that shown in FIGS. 3A and 3B, and may be a shape as shown in FIGS.

In the first and second embodiments described above, the surface of the portion of the shaft portion (11) where the concave portion is formed (the small diameter portion (11b) or the processed portion (11c)) excluding the concave portion. Is considered to be a smooth surface.
This is because if a burr or the like protrudes from the surface of a portion other than the concave portion in the shaft portion, the gasket may be damaged when incorporated in the dry battery.

FIG. 4 is a partially cutaway cross-sectional view of a dry battery incorporating the negative electrode current collector according to the present invention.
As shown in FIG. 4, the negative electrode current collector (1) is disposed in the axial center portion of the dry battery (2).
That is, the dry battery (2) includes a bottomed cylindrical metal container (21) that also serves as a positive electrode terminal, and a hollow cylindrical positive electrode mixture that is housed in the metal container (21) and press-molded at a predetermined pressure. (22), a gelled negative electrode (24) filled inside the positive electrode mixture (22) via a separator (23), a sealing cap (25) and a gasket (26), and a gelled negative electrode ( And 24) a negative electrode current collector (1).

  As a dry battery in which the negative electrode current collector according to the present invention is incorporated, in addition to a general alkaline dry battery using manganese dioxide as a main component of the positive electrode material, a nickel dry battery using nickel oxyhydride as the main component of the positive electrode material Is mentioned.

According to the negative electrode current collector for a dry battery according to the present invention, a configuration in which a concave portion is provided in a thinned portion (small diameter portion) while the shaft portion is thinned (first embodiment) or a concave portion in which the shaft portion is shortened. By adopting the configuration (second embodiment) in which the material is provided, the volume of the material can be reduced without reducing the surface area of the current collector (1). Therefore, it is possible to reduce the material cost without causing a decrease in current collection efficiency due to a decrease in contact area with the gelled negative electrode (24).
In addition, the fixed range (11a) on the head side of the shaft portion, which is a portion that comes into contact with the sealing cap (25) and the gasket (26) when assembled as a dry battery, is not small in diameter and has a concave portion. Since it is not formed, leakage of the gelled negative electrode (24) is prevented.

The negative electrode current collector (1) according to the present invention is produced through the following steps.
The first step is a step of drawing (drawing) the wire with a die, and the second step is a step of cutting the drawn wire into a predetermined dimension. This is done as follows.
First, as shown in FIG. 5, the wire rod (1A) is sandwiched between feed rolls (2A) and (2B) and rotated to supply the wire rod (1A) to the through hole (71) of the die (7). The tip of the wire rod (1A) coming out from the hole (71) is received by the stopper (8) and cut into a predetermined dimension by the cutting knife (9).

In the present invention, iron, copper, copper alloy, or the like is used as the material for the wire (1A). However, using iron is preferable because of the following advantages.
First, since it is cheaper than copper or copper alloy, the manufacturing cost can be kept low.
Second, since it has higher strength than copper or copper alloy, it is difficult to bend during transportation, plating treatment, incorporation into the battery, etc., and a stable high quality dry battery can be obtained.
Thirdly, since electrolytic plating is easier than copper and copper alloys, plating can be easily attached and less time is required for plating, which reduces the cost of plating and facilitates mass production. In addition, since the substrate is not exposed, hydrogen gas is not generated when it is incorporated in a dry battery.

In the present invention, it is preferable to use iron composed of 0.03% by weight or less of carbon and the balance of iron and inevitable impurities as iron used as the material of the wire.
The reason for this is that when iron having a carbon content of 0.03% by weight or less is used, a plating film is uniformly formed in a short time during the plating process, and a reduction in manufacturing cost and an improvement in quality can be achieved. Because.

The third step is a step of performing cold forging (cold forging) processing on the wire cut to a predetermined size and forming it into a predetermined shape (the shape shown in FIG. 1 (a) or FIG. 3 (c)), Specifically, this step is performed as follows.
The wire (1A) cut to a predetermined size is pushed into the die (4) with the first punch (3) having a wide-diameter opening (31) as shown in FIG. The tip portion (13) is formed by drawing the tip by a tapered portion (41) provided on the base, and the base end thereof is expanded in diameter by the wide-diameter opening (31) of the first punch (3). (See FIG. 7). In addition, when shape | molding in the shape shown to Fig.1 (a), the shape of die | dye (4) is a little different from the thing of illustration.
Next, as shown in FIG. 8, instead of the first punch (3), the second punch (5) having a circular recess (51) is further pressed against the die (4) side to the base end of the wire. The head (12) is formed, and then, as shown in FIG. 9, the second punch (5) is retracted and the molded product (1) is pushed out by the knockout pin (6).

  5 to 9, (10) is a mold body, (6A) is a knockout rod to which a knockout pin is attached, and the movement means for moving the knockout rod (6A) in the pushing direction is shown. Is omitted.

  In the fourth step, the above-described concave machining or the above-described concave processing or the shaft portion of the molded product obtained in the first to third steps (the shape shown in FIG. 1A or FIG. 3C) is used. This is a step of obtaining a workpiece having the shape shown in FIG. 1B or FIG. 3A and FIG.

The fifth step is a step of plating the surface of the wire (preferably iron wire) formed in a predetermined shape.
As the plating treatment, galvanization or tin plating, or plating with a two-layer structure described later is performed.
Zinc plating is performed by electrolytic plating, but tin plating may be performed by electrolytic plating or electroless plating. However, in the present invention, it is preferable to use electrolytic plating.
The reason is that by using electrolytic plating, stable and uniform plating can be formed, and a negative current collector with high dimensional accuracy can be obtained. The thickness of zinc plating or tin plating is 2 to 5 μm.

When the second layer is plated in the fifth step, the inner layer is plated with copper and the outer layer is plated with tin, or the inner layer is plated with copper and the outer layer is plated with zinc. .
When these two-layer structures are employed, the plating thickness of each layer is, for example, that the inner layer has a thickness of 1 to 2 μm and the outer layer has a thickness of 2 to 5 μm.
By forming such a two-layered plating, even if there is a defect such as a pinhole in the outer layer plating film, the inner layer plating film prevents the iron material from being exposed, and more hydrogen gas is generated. This can be prevented more reliably.

  By plating the surface, the current collector surface itself and the metal (Fe, Ni, Cr, Mo, W, V, As, etc.) that make up the die that dig into the surface and the metal fines made of these oxides It is possible to prevent the generation of hydrogen gas when the piece is coated by plating and incorporated in a dry battery.

The sixth step is a step of applying a deactivation process.
The non-conducting treatment is performed by immersing the surface of the negative electrode current collector after plating in an acidic solution such as nitric acid after being activated by etching.
Thereby, since an oxide film is produced | generated on the surface of a negative electrode electrical power collector, generation | occurrence | production of hydrogen gas can be prevented when it uses by incorporating in a dry battery.

After the deactivation treatment is performed, a sealing treatment is performed as a seventh step.
The sealing treatment is performed by immersing the negative electrode current collector that has been subjected to the passivation treatment in a solution containing a surfactant.
As a result, the negative electrode current collector is further deactivated (it is difficult to oxidize and the corrosion resistance is improved), and the effect of preventing the generation of hydrogen gas can be further enhanced when the negative electrode current collector is incorporated in a dry battery. Furthermore, since the surface is smoothed, the effect of preventing damage to the packing when assembled in a dry battery is also obtained.

  Through the first step to the seventh step described above, the manufacture of the negative electrode current collector for a dry battery according to the present invention is completed, and the negative electrode current collector manufactured in this way is an alkaline dry battery or It is used by being incorporated into the axial center of a nickel dry battery.

  The present invention is used as a negative electrode current collector incorporated in an alkaline dry battery or nickel dry battery.

It is a front view which shows 1st embodiment of the negative electrode collector for dry batteries which concerns on this invention. It is a figure which shows the example of the other shape of a recessed part. It is a figure which shows 2nd embodiment of the negative electrode collector for dry batteries which concerns on this invention. It is a partial notch sectional view of the dry battery incorporating the negative electrode collector which concerns on this invention. It is a figure which shows 1 process of the manufacturing method of the negative electrode collector which concerns on this invention. It is a figure which shows 1 process of the manufacturing method of the negative electrode collector which concerns on this invention. It is a figure which shows 1 process of the manufacturing method of the negative electrode collector which concerns on this invention. It is a figure which shows 1 process of the manufacturing method of the negative electrode collector which concerns on this invention. It is a figure which shows 1 process of the manufacturing method of the negative electrode collector which concerns on this invention. It is a front view which shows the conventional negative electrode collector for dry batteries.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Negative electrode current collector 11 Shaft part 11a Head-side fixed range 11b Small diameter part 12 Head part 13 Tip part D The whole or a part of the length direction diameter excluding the fixed range d The diameter L1 of the fixed range part Length L2 Length of the portion where the recess was formed

Claims (6)

It is composed of a cylindrical shaft portion, a large-diameter disk-shaped head portion provided near the base end of the shaft portion, and a substantially conical tip portion provided at the tip of the shaft portion,
The shaft portion has a whole or a part in the length direction excluding a certain range on the head side smaller in diameter than the certain range portion, and a recess is formed on the surface of the small diameter portion. A negative electrode current collector for a dry battery. It is composed of a cylindrical shaft portion, a large-diameter disk-shaped head portion provided near the base end of the shaft portion, and a substantially conical tip portion provided at the tip of the shaft portion,
The shaft portion has a recess formed on the entire surface or a part of the surface in a length direction excluding a certain range on the head side, and the length is compared with the length when the recess is not formed. The negative electrode current collector for a dry battery is shortened by a length corresponding to the surface area increased by the formation of the recess.   The negative electrode current collector for a dry battery according to claim 1, wherein the concave portion is formed by a rolling process.   The negative electrode current collector for a dry battery according to claim 3, wherein the rolling process is a knurling process.   5. The negative electrode current collector for a dry battery according to claim 1, wherein a surface of a portion of the shaft portion where the concave portion is formed, excluding a portion recessed as the concave portion, is a smooth surface. body.   Electrode plating or electroless plating is performed, The negative electrode collector for dry batteries according to any one of claims 1 to 5.

Images