JP2003109600A - Current collector material for battery, and battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current collector material enabling a battery to have high capacity, enabled to carry out a high rate discharge, and to provide a battery using the same. SOLUTION: A current collector comprises an unwoven fabric 11, and a plated film 12 formed on the unwoven fabric 11. The area of the cross section of the plated area on the surface of the unwoven fabric fiber ranges between 20-130 μm<2> . It is preferable to apply a treatment making the unwoven fabric 11 hydroforbic, and to make the fineness of the fiber composing the unwoven fabric 11 not less than 1.5 dtex. The current collector is enabled to use for various primary batteries and secondary batteries, and it is recommendable to use it for an alkali secondary battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collector for a battery and a battery using the same, and more particularly to a current collector for a battery obtained by plating a non-woven fabric with a predetermined plating cross-sectional area and a battery using the same.

[0002]

2. Description of the Related Art Conventionally, batteries, especially alkaline secondary batteries, are
Since it is highly reliable and can be made compact and lightweight, it is widely used as a power source for various devices from portable equipment to large industrial equipment. In most of the alkaline secondary batteries, a nickel hydroxide electrode is used as the positive electrode. The nickel hydroxide electrode has a structure in which a positive electrode active material for causing a battery reaction is carried on a current collector that shares the current collecting function. As the current collector in that case, a sintered nickel plate obtained by sintering nickel powder, a punching nickel plate, or the like has been widely used. The capacity of the battery is determined by the amount of the active material to be filled in the voids of the nickel plate, and the filling amount of the active material is determined by the void ratio of the nickel plate. Therefore, the void ratio of the nickel plate should be maximized. Is desired.

However, the sintered nickel plate has a punching nickel plate as a base material, and the base material has a porosity of 75 to 8
Since it is as low as 0% and the nickel content in the nitrate solution is low, it is necessary to repeat the filling cycle of impregnation and neutralization several times or more to fill the predetermined amount of the active material. It is difficult to fill the active material with a high density because the penetration into the nickel plate deteriorates. Therefore, recently, in order to increase the packing density of the active material of the current collector with the demand for smaller size and higher capacity of the battery, the porosity is large and hence the packing density of the active material can be increased in three dimensions. A current collector made of a mesh structure is used.

As the current collector having this three-dimensional network structure, for example, as described in JP-A-8-329956, a non-woven fabric made of organic fibers is plated with a predetermined amount of nickel to heat the non-woven fabric. Without disassembling and removing
There is known a current collector having a three-dimensional network structure in which only the surface of the nonwoven fabric can exhibit conductivity.

Further, a current collecting material for an alkaline secondary battery, which is provided with a non-woven fabric and a nickel plating film formed on the surface of the non-woven fabric, is also known.

[0006]

However, the non-woven fabric made of the organic fiber used for the current collector disclosed in JP-A-8-329956 has a large amount of nickel plating applied to the surface thereof. Since the porosity becomes low and the pore size becomes small at the same time, there is a problem that it is difficult to sufficiently fill the active material of the battery and it is difficult to increase the capacity of the battery.

Further, the current collector having the nickel plating film formed on the surface of the conventional non-woven fabric has a problem that the surface resistance is high and high-rate charge / discharge is difficult.

The present invention has been made to solve the above-mentioned conventional problems, and a current collector capable of increasing the capacity of a battery and capable of producing a battery capable of high-rate charging / discharging and a collector thereof. An object of the present invention is to provide a battery using.

[0009]

The invention according to claim 1 of the present invention is a current collector for a battery comprising a nonwoven fabric and a plating film formed on the surface of the nonwoven fabric, wherein the plating film is formed. The cross section of the plated non-woven fiber surface is 20
a battery current collector, which is a μm ² ~130μm ^2.

The invention according to claim 2 is characterized in that the non-woven fabric is hydrophilized.

The invention according to claim 3 is characterized in that the constituent fibers of the non-woven fabric include fibers having a fineness of 1.5 dtex or more.

[0012] The invention according to claim 4 is a battery characterized by using the current collector according to any one of claims 1 to 3.

According to the invention of claim 1, since the plating sectional area of the plating nonwoven fiber surface is 20μm ² ~130μm ^2, low surface resistivity of the plating film can be sufficiently filled with the active material, a high capacity battery It is possible to manufacture a battery that can be made into a high-speed charge and discharge.

According to the second aspect of the present invention, since the non-woven fabric is hydrophilized, the adhesion of the fibers of the non-woven fabric to the plating film is increased, and the surface resistance of the plating film is decreased, so that high-rate charging / discharging is performed. It will be possible.

According to the invention of claim 3, as the constituent fibers of the non-woven fabric, fibers having a fineness of 1.5 dtex or more are included, so that the porosity is increased and the filling amount of the active material can be increased and the plating amount is increased. Can be easily adjusted to obtain a desired plating cross-sectional area.

According to the invention of claim 4, the battery is claim 1.
Since the current collector described in any one of 1 to 3 is used,
A battery having a high capacity and capable of high-rate charge / discharge can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the current collector 10 of the present invention.
Has a nonwoven fabric 11 and a plating film 12 formed on the surface of the nonwoven fabric 11. Further, the plating cross-sectional area of the surface of the plated non-woven fabric on which the plated film 12 is formed is 20 μm.
It is in the range of ^{2 to} 130 μm ² . The current collector according to the present invention is
Although it can be used for various primary batteries and secondary batteries, for example, alkaline batteries and lithium batteries, an alkaline secondary battery will be described as an example of a desirable battery.

First, the non-woven fabric 11 is composed of either one or both of a polyolefin fiber and a polyamide resin fiber. Examples of the resin component of the polyolefin fiber include, for example, polyethylene, polypropylene, polymethylpentene, ethylene-propylene copolymer, ethylene-butene-propylene copolymer, ethylene-vinyl alcohol copolymer, and the like. It is preferable to include one or more components. As the resin component of the polyamide resin fiber,
Examples thereof include nylon 6, nylon 66, nylon 12, or a copolymer of nylon 6 and nylon 12, and the polyamide resin fiber preferably contains one or more of these resin components.

Nonwoven fabric 11 composed of either or both of polyolefin fibers and polyamide resin fibers
The fact that polyolefin fibers and polyamide resin fibers themselves have already been used as separators for batteries, and polyolefin fibers and polyamide resin fibers are used even when they are contacted with a 20 to 35 wt% KOH aqueous solution, This is because it does not dissolve, has no change in physical properties, has excellent alkali resistance, and can be purchased at a very low price and has high versatility.

In the case of polyolefin fibers, a polyethylene resin or a polypropylene resin having excellent alkali resistance and acid resistance is particularly preferable. The polyolefin fibers may be polypropylene resin only, polyethylene resin only, or fibers obtained by combining these resins. In particular, a core-sheath type composite fiber in which the periphery of polypropylene (core) is covered with polyethylene (sheath) is suitable because it can simultaneously satisfy both alkali resistance and strength characteristics. Although polyolefin fibers or polyamide fibers are shown in FIG. 1, the present invention is not limited thereto.

The fibers constituting the nonwoven fabric 11 are not particularly limited, but it is preferable to use crimped fibers. When the non-woven fabric 11 contains crimped fibers, the non-woven fabric 11 becomes bulky and its void volume increases, and a large amount of active material can be filled, resulting in a high-capacity battery. In addition, since the average pore size becomes large, it becomes easy to fill the active material. The crimped fiber preferably has a crimping number of 3 fibers / inch or more, more preferably 5 fibers / inch or more. Also, in order to maintain an appropriate porosity,
The crimped fibers are preferably mixed in the nonwoven fabric in an amount of 5% by weight or more, more preferably 20% by weight or more, and 50% by weight or more. More preferable. The crimped fiber may be mechanically crimped, or may be a fiber that is crimped by heat. Examples of the fiber which is crimped by heat include a side-by-side fiber made of two kinds of resins having different shrinking temperatures or an eccentric type core-sheath type fiber.

As the method for producing the nonwoven fabric 11, a card method, an air-laying method, a dry method such as a melt blow method or a spunbond method for continuously forming a sheet from a spun state, or a method in which fibers are dispersed in water It can be obtained by forming fiber webs by a wet method or the like and then appropriately binding the fibers together. In particular, since the non-woven fabric produced from the fibrous web obtained by the wet method has less variation in unit weight and thickness as compared with the non-woven fabric produced from the fibrous web obtained by the dry method, a uniform current collector can be obtained. it can. Therefore, when this current collector is used, an electrode having a uniform thickness is formed, and when the electrode is wound, a pole group having excellent adhesion can be formed, and as a result, a battery having excellent charge / discharge characteristics can be obtained.

As a method of joining the fibrous webs, for example, a method of enhancing the strength characteristics by performing entanglement treatment or heat treatment can be exemplified. As the entanglement treatment, for example, a water entanglement treatment that impacts a very fine high-pressure water jet, a entanglement treatment using a needle punch, or the like can be adopted. When the fiber web is subjected to the entanglement treatment, the fibers are entangled with each other, the number of contact points 11a between the fibers is increased, the strength characteristics are improved, and the porosity can be adjusted to an appropriate value. The heat treatment is performed to locally fuse the fibers at the contact points 11a of each other to improve the overall strength characteristics. However, if the heat treatment is performed at a temperature equal to or higher than the thermal decomposition temperature of the fiber, the fiber thermally decomposes and disappears. Therefore, it is necessary to set the treatment temperature below the thermal decomposition temperature of the fiber.

The temperature of the heat treatment is set to a temperature lower than the thermal decomposition temperature of the fiber and a temperature higher than the melting point of the fiber and 30 ° C. higher than the melting point, but within that temperature,
If the temperature is too low, the heat fusion between the fibers cannot be said to be sufficient, so that the strength of the obtained non-woven fabric becomes low, and buckling or the like begins to occur when the active material synthetic paste is filled. On the other hand, if the temperature is too high, the fibers are melted and the porosity is lowered, which also lowers the packing density of the active material synthetic paste. Therefore, when the above-mentioned core-sheath type composite fiber in which polypropylene is covered with polyethylene is used as the fiber, the heat treatment temperature is preferably 110 to 140 ° C. The entanglement treatment and the heat treatment may be performed independently, but it is preferable to perform the entanglement treatment and then the heat treatment, because the strength characteristics of the obtained nonwoven fabric are significantly improved.

The nonwoven fabric 11 preferably has a porosity of 70% or more. The porosity in this case refers to the percentage of pores with respect to the volume of the entire nonwoven fabric. 70% porosity
If it is made smaller, the strength characteristics of the obtained non-woven fabric 11 are improved, but the packing density of the active material synthetic paste becomes low,
As a result, the performance of the electrode current collector 10 of the high capacity battery is deteriorated. On the other hand, if the porosity is too high, the strength is significantly reduced, so that the porosity is preferably 80 to 98%.

As the current collector 10, a non-woven fabric 11 composed of either one or both of the above-mentioned polyolefin fiber or polyamide resin fiber is used. Preferably,
The non-woven fabric 11 may be subjected to a hydrophilic treatment, which increases the degree of adhesion between the fibers of the non-woven fabric and the plating film and lowers the surface resistance of the plating film, enabling high-rate charging / discharging. The hydrophilic treatment is performed by sulfonation treatment, fluorine gas treatment or vinyl monomer graft treatment, surfactant treatment, hydrophilic resin application treatment and discharge treatment. The current collector 10 is made by plating the hydrophilic non-woven fabric 11.

Generally, polyolefin-based materials such as polypropylene and polyamide-based materials have poor affinity with the plating solution and poor adhesion between the fiber surface and the plating film. On the other hand, the hydrophilic treatment improves the affinity of the plating solution with the fiber surface and firmly binds to nickel ions, improving the conductivity and the adhesion to the metal plating formed on the fiber surface. Is planned.

Examples of the hydrophilization treatment include sulfonation treatment, fluorine gas treatment, vinyl monomer graft polymerization, surfactant treatment, discharge treatment, and hydrophilic resin application treatment. In particular, the sulfonation treatment, the fluorine gas treatment or the vinyl monomer grafting treatment is preferable in an aqueous solution of 20 to 35 wt% KOH, which is an electrolyte used for a battery, because the plating film does not drop out and the surface resistance does not increase for a long period of time. .

The sulfonation treatment is not particularly limited, but for example, fuming sulfuric acid, sulfuric acid, sulfur trioxide,
There is treatment by immersion in chlorosulfuric acid, sulfuryl chloride or the like. Among these, the sulfonation treatment with fuming sulfuric acid is preferable because it has high reactivity and can be sulfonated relatively easily. The fluorine gas treatment is also not particularly limited, but is selected from, for example, fluorine gas diluted with an inert gas (such as nitrogen gas and argon gas), oxygen gas, carbon dioxide gas, and sulfur dioxide gas. However, a treatment by contacting with a mixed gas with at least one kind of gas can be mentioned. It should be noted that the method of previously adhering sulfur dioxide gas to the nonwoven fabric and then contacting it with fluorine gas is a more efficient and permanent hydrophilization treatment method. Also for vinyl monomer grafting,
Although not particularly limited, for example, the nonwoven fabric is impregnated with at least one graft polymerization liquid selected from acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, vinyl pyridine, or styrene, and then irradiated with ultraviolet rays. The processing can be mentioned. Among these, acrylic acid is preferable because it does not drop the plating film or increase the surface resistance in a KOH aqueous solution as an electrolytic solution for a long time.

The hydrophilic treated non-woven fabric thus obtained is plated. This plating treatment is preferably an electroless plating method. If necessary, the electroless plating film 12a formed by the electroless plating method is further formed with an electrolytic plating film 12b by the electrolytic plating method, and the surface of the nonwoven fabric 11 is formed. Are coated with the plating film 12. The metal to be plated is typically nickel, but various metals such as copper, gold and aluminum can be used depending on the battery used.

In the present invention, the plating cross-sectional area of the surface of the plated non-woven fabric on which the plating film 12 is formed is 20 μm.
It is preferably in the range of ^{2 to} 130 μm ² . If the plating cross-sectional area is less than 20 μm ² , the surface resistance of the plating film 12 becomes high and high rate charging / discharging becomes difficult.
It is more preferably 0 μm ² or more, still more preferably 40 μm ² or more. In addition, the plating cross-sectional area is 130
If it exceeds μm ² , the fiber becomes thick and the porosity decreases,
Since the filling amount of the active material decreases and it becomes difficult to increase the capacity of the battery, it is more preferably 120 μm ² or less.
More preferably, it is less than or equal to μm ² .

In order to obtain such a plating cross section,
It is desirable that the fibers forming the non-woven fabric that is the basis of the plated non-woven fabric include fibers having a fineness of 1.5 dtex or more. More preferably, it contains 2.5 dtex or more fibers, and most preferably 4 dtex or more fibers. The upper limit is not particularly limited, but fibers having a fineness of about 30 dtex are suitable. By using such a relatively thick fiber, the interval between adjacent fibers is increased, the porosity is increased, and the filling amount of the active material can be increased. Further, the desired plating cross-sectional area can be easily obtained. Such a relatively thick fiber is preferably contained in the nonwoven fabric in an amount of 10 mass% or more, more preferably 20 mass% or more.

Here, the electroless plating method is specifically divided into a catalyst applying step and an electroless plating step. The catalyst application step includes a method of treating with stannous chloride in hydrochloric acid solution and then catalyzing with palladium chloride in hydrochloric acid solution, and a method of immobilizing with only hydrochloric acid solution of palladium chloride containing an amino group of a curing agent. However, the former method is preferable because it provides the most uniform plating film thickness. The electroless plating step is generally a method of reducing nickel with a reducing agent in an aqueous solution containing nickel salt such as nickel nitrate, nickel chloride and nickel sulfate, and if necessary, a complexing agent,
A pH adjuster, a buffer, a stabilizer, etc. are added. In order to obtain a nickel film having a particularly high purity, it is preferable to use a hydrazine derivative such as hydrated hydrazine, hydrazine sulfate and hydrazine oxide as a reducing agent. The property of the non-woven fabric during electroless plating is a method of continuously plating from a catalyst applying tank to a plating tank while winding a continuous long length,
Examples of the method include a method in which a cheese dyeing machine is used to forcibly circulate a liquid and plating is performed in a state of being rolled up. In the treatment in the state of being rolled up, only the catalyst applying step or only the electroless plating step may be performed, or both of these steps may be performed in the state of being rolled up.

If necessary, an electrolytic plating film 12b is further formed. The electrolytic plating method is performed using a plating bath.
Known plating baths are a Watt bath, a chloride bath, and a sulfamic acid bath. Additives such as a pH buffer and an interface buffer may be used for this. By connecting the electrolessly plated non-woven fabric to this bath as the cathode and connecting the nickel counter electrode plate to the anode and applying a DC or pulse intermittent current,
After forming the electroless plated film 12a, the electrolytic plated film 12b is further formed.

The current collector made in this way uses the non-woven fabric 11 composed of either one or both of polyolefin-based fibers and polyamide resin-based fibers that have been used as separators for batteries. Relatively reliable. Further, since the non-woven fabric 11 is subjected to a hydrophilic treatment (particularly a sulfonation treatment, a fluorine gas treatment or a vinyl monomer graft treatment), the affinity of the non-woven fabric with a plating solution is improved, and the hydrophilic treated non-woven fabric is nickel-plated. Since the treatment is performed, the nonwoven fabric 11 is firmly bonded to nickel ions. As a result, it is possible to obtain the current collector 10 having improved conductivity and improved adhesion to the metal plating formed on the fiber surface.

The non-woven fabric preferably has a plurality of pores penetrating from one surface to the other surface.
If multiple pores are scattered in the non-woven fabric, these pores are also filled with the active material, so that the filling amount of the active material is increased and the capacity of the battery, especially the alkaline secondary battery is increased. You can The non-woven fabric having fine pores is preferably formed by so-called punching in which a plurality of fine pores are formed by punching, but may be formed by locally dissolving or disappearing the non-woven fabric by heat or laser processing. .

Next, an alkaline secondary battery will be described with reference to the drawings as an example of a battery using the current collector according to the present invention.

As shown in FIG. 2, a battery 101 is an alkaline secondary battery using a current collector made of nickel-plated non-woven fabric subjected to hydrophilic treatment (for example, sulfonation treatment, fluorine gas treatment or vinyl monomer graft treatment). And a strip-shaped positive electrode 102 and a strip-shaped negative electrode 103 made of this current collector.
Equipped with. The first separator 104a is interposed between the positive electrode 102 and the negative electrode 103, and the roll-shaped power generator 106 in which the second separator 104b is interposed inside the positive electrode 102 is provided (FIG. 2). And this battery 10
1 includes a conductive battery case 107 that houses the power generator 106 and also serves as a negative electrode, and an encapsulation plate 108 that seals the case 107 and also serves as a positive electrode.

For the positive electrode 102, the above-mentioned current collector is formed in a strip shape, and after crushing the place where the terminal is attached, the voids of the entire current collector are filled with the positive electrode paste containing the positive electrode active material, and then dried and rolled. Then, the nickel piece 102a as an external terminal for current collection is spot-welded to the crushed portion. Further, the negative electrode 103 is formed by forming the above current collector into a strip shape, crushing the places where the terminals are attached, filling the voids of the entire current collector with the negative electrode paste containing the negative electrode active material, and then drying and rolling. Then, a nickel piece (not shown) as an external terminal for collecting electricity is spot-welded to the crushed portion. On the other hand, the separator 104 is formed of a porous sheet in a band shape, and has a first separator 104 a interposed between the positive electrode 102 and the negative electrode 103, and a second separator 104 b laminated on the inner surface of the positive electrode 102. The first and second separators 104a and 104b are configured to prevent a short circuit between the positive electrode 102 and the negative electrode 103 and to hold the electrolytic solution.

The conductive battery case 107 is formed in a cylindrical shape having a can bottom 107a, and the enclosing plate 108 is constructed so as to close the opening at the upper end of the battery case 107. The battery case 107b is configured so that the power generator 106 can be housed so that the negative electrode 103 contacts the inner peripheral surface of the battery case 107b. In addition, a protrusion 108 that forms the positive electrode terminal of the battery is formed in the center of the encapsulation plate 108.
a is formed. Further, a lower insulator 109a is interposed between the can bottom 107a and the power generator 106. Power generator 10
6 is a battery case 107 in which a lower insulator 109a is inserted.
The upper insulator 10 is inserted into the upper end of the power generator 106.
9b is arranged.

The lower insulator 109a is formed with a slit through which the nickel piece spot-welded to the negative electrode 103 can be inserted, and the upper insulator 109b is formed with a slit through which the nickel piece 102a spot-welded to the positive electrode 102 can be inserted. To be done. The nickel piece spot-welded to the negative electrode 103 is inserted into a slit formed in the lower insulator 109a and protrudes toward the can bottom 107a side, and the nickel piece 102a spot-welded to the positive electrode 102 is a slit formed in the upper insulator 109b. Is configured to pass through and to protrude toward the sealing plate 108 side. The nickel piece protruding from the slit of the lower insulator 109a is connected to the can bottom 107a, and the nickel piece 10 protruding from the slit of the upper insulator 109b.
2a is connected to the sealing plate 108.

The upper insulator 109b is the battery case 107.
The sealing plate 1 in which the ring-shaped constricted portion 107b is formed in the upper portion of the battery case 107 in the vicinity of the opening, and the nickel piece 102a of the positive electrode 102 is connected thereafter.
08 is arranged in the constricted portion 107b via a ring-shaped insulating packing 111. Then battery case 107
The upper end edge of the battery is folded back and the outer peripheral edge of the encapsulating plate 108 is covered with the insulating packing 111 so that the encapsulating plate 108 is electrically insulated from the battery case 107, and the battery case is sealed by the encapsulating plate 108.

In the battery 101 thus constructed, the second separator 104b, the positive electrode 102, and the first separator 1
04a and the negative electrode 103 are laminated in this order. In such a laminated state, the power generator 106 is manufactured by winding the negative electrode 103 in a roll shape so that the negative electrode 103 is on the outer side. However, the current collector obtained by applying nickel plating to the hydrophilized nonwoven fabric is
The positive electrode 1 using this current collector is relatively flexible as compared with the conventional current collector having a net-like skeleton made of nickel.
02 and the negative electrode 103 are also relatively flexible, are relatively easy to wind in a roll shape, and facilitate the assembly of the battery 101 itself.

Further, since the current collector obtained by nickel-plating the non-woven fabric subjected to the hydrophilic treatment has high nickel-plating adhesion, the quality of the plating film is changed or partially missing even when the battery is assembled and charged and discharged repeatedly. There is no such thing. Therefore, the battery using this current collector can have higher rate discharge characteristics and higher capacity than conventional batteries.

In the above-described embodiment, the battery in which the power generator 106 wound in a roll shape is inserted in the cylindrical battery case 107 has been described, but the battery case may have a rectangular tube shape. , The positive electrode 102 as shown in FIG.
And the negative electrode 103 wound into a spiral shape, or FIG.
It may be bent and laminated in a bellows shape as shown in FIG.

[0047]

EXAMPLES Next, examples of the present invention will be described in detail together with comparative examples.

Examples 1 to 4 and Comparative Examples 1 to 4 100% by weight of a core-sheath type composite fiber having a fineness of 6.6 dtex and having a core component of polypropylene and a sheath component of high density polyethylene and a fiber length of 5 mm was dispersed. The slurry,
A fibrous web was formed by a conventional wet papermaking method. This fiber web is heat-treated with a dryer set at 135 ° C. to fuse the sheath component of the core-sheath type composite fiber to give a basis weight of 100 g.
A non-woven fabric having a thickness of 0.8 mm / m ² was prepared. The porosity of this nonwoven fabric was 86%.

This non-woven fabric was subjected to a sulfonation treatment by immersing it in a fuming sulfuric acid solution at 80 ° C., and the resulting hydrophilicized non-woven fabric was subjected to nickel plating treatment. In this nickel plating treatment, the hydrophilic treated non-woven fabric is wrapped around a carrier of a dyeing machine, a refining agent is circulated and washed with water, and then an aqueous solution containing 10 g / liter of stannous chloride and 20 ml / liter of hydrochloric acid is circulated and washed with water. Then, an aqueous solution containing 1 g / liter of palladium chloride and 20 ml / liter of hydrochloric acid was circulated to carry out catalysis.

After that, further washing with water was performed to obtain nickel sulfate 1
8 g / liter, sodium citrate 109 / liter, hydrated hydrazine 50 ml / liter, 25% ammonia water 100 ml / liter, each concentration of electroless nickel plating solution, the nickel plating weight relative to the total weight of the current collector after plating The amount of nickel-containing liquid described in Table 1 below was heated to 80 ° C. and circulated. 1
After the plating solution was circulated for a time to become almost transparent, the circulation was stopped, the nonwoven fabric was taken out, washed with water, and further dried to obtain a current collector.

[0051]

[Table 1] In Table 1, the plating cross-sectional area is 20 μm ^{2 to} 130
The current collectors having a size of μm ² are shown as Examples 1 to 4, and the current collectors having a plating cross-sectional area outside this range are shown as Comparative Examples 1 to 4. A battery test was performed on these current collectors. The measuring method is as follows.

First, in Table 1, the packing density of active material (g / c
m³) Is nickel hydroxide (Ni (O
H)₂) After measuring the weight W1 (g) of the current collector
Then, subtract the weight W (g) before filling the active material from this weight,
The active material filling amount (W1-W) is calculated. Next, the active material
Thickness T (cm) and area A (cm) of the current collector after filling
²) Is measured. Filling the active material from these measurement results
Density is the packing density (g / cm ³) = (W1-W) / (A
XT).

The fiber specific gravity (polypropylene / polyethylene) (g / cm ³ ) of the nonwoven fabric was 0.94, and the specific gravity (g / cm ³ ) of nickel metal was 8.9. From these values, the fiber specific gravity (SG) after plating (g / cm
³ ) is (current collector weight (g)) / {(nickel weight /
8.9) + (nonwoven fabric weight / 0.94)}.

Next, in Table 1, the porosity (%) of the current collector is
The porosity (%) = {1-W / (t × SG)} × 100 was calculated from the thickness t (μm) of the current collector and the basis weight W (g / m ² ). The utilization rate (%) was measured as follows. That is, an AA (AA) type battery (capacity 1200 mAh) was produced by using the current collectors of Examples and Comparative Examples for the positive electrode and nickel foam for the negative electrode, and the temperature was 20 ° C. and 0.1 C.
The battery was activated by charging and discharging. By changing the test current,
Charge and discharge were performed every 5 cycles. Each test rate 0.1C
The test current for ~ 3C is 0.1 for 0.1C.
× 1200 (mAh), 1C for 1 × 1200 (m
Ah) 2 × 1200 (mAh) for 2C and 3 × 1200 (mAh) for 3C. Utilization ratio(%)
Is the utilization rate (%) = {discharge capacity (average value of 5 measurements)
÷ 1200} × 100. Plating ratio (%)
Was calculated by the following formula: plating ratio (%) = {nickel weight (g) ÷ current collector weight W (g)} × 100.

As is clear from Table 1, when the plating cross-sectional area exceeds 130 μm ² , the fiber after plating becomes thick,
Since the porosity decreases, the filling amount of the active material becomes insufficient.
It was also found that when the plating cross-sectional area is less than 20 μm ² , the plating amount is small and the surface resistance is high, so that a sufficient capacity cannot be obtained by high rate charge / discharge. On the other hand, the plating cross-section area of the plated non-woven fiber surface is 20 μm ^{2 to} 13
When it is in the range of 0 μm ² , the surface resistance of the plating film is low,
It has been found that a battery can be obtained in which the active material can be sufficiently filled, the battery can have a high capacity, and high-rate charging / discharging can be performed.

[0056]

As described above, according to the invention of claim 1, the plating cross-sectional area of the surface of the plated nonwoven fabric fiber is 20 μm.
Since it is ^{2 to} 130 μm ² , the surface resistance of the plating film is low, the active material can be sufficiently filled, the capacity of the battery can be increased, and a battery capable of high rate charge and discharge can be manufactured.

According to the second aspect of the present invention, since the non-woven fabric is hydrophilized, the adhesion of the fibers of the non-woven fabric to the plating film increases and the surface resistance of the plating film decreases, so that high-rate charging / discharging occurs. It has the effect of being possible.

According to the invention of claim 3, as the constituent fibers of the non-woven fabric, fibers having a fineness of 1.5 dtex or more are included, so that the porosity is increased and the filling amount of the active material can be increased and the plating amount is increased. There is an effect that a predetermined plating cross-sectional area can be easily obtained by adjusting.

According to the invention of claim 4, the battery is claim 1.
Since the current collector described in any one of 1 to 3 is used,
It is possible to obtain a battery having a high capacity and capable of high-rate charge / discharge.

[Brief description of drawings]

FIG. 1 is a partially enlarged view of a current collector of the present invention including a nonwoven fabric and a plating film.

FIG. 2 is a perspective view in which a part of the alkaline secondary battery of the present invention is cut away.

FIG. 3 AA of FIG. 2 in which the current collector is spirally wound
It is a line sectional view.

FIG. 4 is a cross-sectional view corresponding to FIG. 3, in which a current collector is wound in a spiral shape.

5 is a cross-sectional view corresponding to FIG. 3 in which current collectors are bent and stacked in a bellows shape.

[Explanation of Codes] 10 ... Current collector, 11 ... Nonwoven fabric, 11a ... Contact point, 12 ...
Plating film, 12a ... Electroless plating film, 12b ... Electrolytic plating film, 101 ... Alkaline secondary battery, 102 ... Positive electrode, 10
2a ... Nickel piece, 103 ... Negative electrode, 104 ... Separator, 104a ... First separator, 104b ... Second separator, 106 ... Generator, 107 ... Battery case, 107a
… Can bottom, 108… Protrusion, 109a… Lower insulator, 109
b ... Upper insulator.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nishihori Nei             7 Kitatone, Oaza, Sowa-machi, Sarushima-gun, Ibaraki             Inside Baireen Co., Ltd. (72) Inventor Toshiaki Takase             7 Kitatone, Oza, Sowa-machi, Sarushima-gun, Ibaraki             Inside Baireen Co., Ltd. (72) Inventor Masataka Tanaka             7 Kitatone, Oza, Sowa-machi, Sarushima-gun, Ibaraki             Inside Baireen Co., Ltd. (72) Inventor Ryoho Mayuzumi             Akita City Akita City 3-6 Ibaraki Stock Association             Company Gemco (72) Inventor Hiroyuki Imai             Akita City Akita City 3-6 Ibaraki Stock Association             Company Gemco F term (reference) 5H017 AA02 AA03 BB08 BB16 CC05                       DD05 EE01 EE04 EE05 EE07                       HH03 HH04                 5H028 BB10 EE01 EE06 EE10 HH05                 5H029 AJ02 AJ03 AK02 AL11 BJ02                       BJ14 BJ15 CJ11 CJ24 DJ07                       DJ15 EJ01 EJ12 HJ04 HJ07

Claims (4)

[Claims] 1. A non-woven fabric and said a battery current collector and a plating film formed on the surface of the nonwoven fabric, plating sectional area 20μm ² ~130μm ² of plating the nonwoven fiber surface in which the plating film is formed A current collector for a battery, characterized in that 2. The current collector for a battery according to claim 1, wherein the non-woven fabric is hydrophilized. 3. The current collector for a battery according to claim 1, wherein the constituent fibers of the non-woven fabric include fibers having a fineness of 1.5 dtex or more. 4. A battery using the current collector according to any one of claims 1 to 3.