JPH11323593A - Porous current collector for battery, electrode, their production and apparatus for production therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and method capable of inexpensively producing a long-sized porous metallic band and electrode suitable for production of current collectors and electrodes for batteries and the porous metallic band and electrode produced by the same. SOLUTION: A conductive drum 12 formed by providing the outer peripheral surface consisting of a conductor part 10 with nonconductor parts 11 in prescribed patterns is immersed into a plating bath 14 and a porous plating layer 15 is formed on the outer peripheral surface of the conductive drum 12 by rotating the conductive drum 12. The conductive drum 12 is further rotated to take the porous plating layer 15 out of the plating bath 14 in the state of keeping the plating layer adhered to the outer peripheral surface. The plating layer is then peeled from the outer peripheral surface by means of a peeling positioning roll 19 and a pair of peeling angle regulating rolls 20, 21 after cooling and is thereafter washed, by which the porous metallic band 15a is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous current collector for a battery mainly made of a metal such as iron, copper or aluminum, an electrode using the same, a manufacturing method and a manufacturing apparatus for manufacturing the same. About.

[0002]

2. Description of the Related Art Conventionally, a number of patents have been issued as a method for producing a metal mesh foil from a plating bath, such as plating on a conductive drum provided with a non-conductive portion and peeling it off. This is a known fact. As an example of a recent patent, there is a method disclosed in JP-A-8-100288. In this manufacturing method, a plating layer is formed by electroplating on a metal drum in which an insulating material is buried in a predetermined pattern on the outer peripheral surface, and the plating layer is exposed from the plating solution to the air to the peeling interface. Range from 0 ° C to 15 ° C
The plating layer and the surface are washed with cold water. In addition, as an effect brought by this manufacturing method, by applying cold water to the plating layer, the adhesion between the metal plating layer and the insulating material is reduced, and the buried insulating material does not fall off the metal drum. It is described that a long and inexpensive metal mesh foil can be manufactured continuously.

[0003]

However, the above-described method for producing a metal mesh foil still has the following problems to be solved. That is, according to the research of the present inventor, since the metal mesh foil manufactured using the same manufacturing method is extremely thin and porous, when peeled at a peel angle other than a proper peel position and peel angle, for example, the previous stage Even when cooled, the foil often breaks, making stable production difficult. Further, this method does not take into account the problem that the cooling water falls into the plating tank and the concentration of the plating solution decreases, and the desired metal foil cannot be obtained.

On the other hand, in recent years, a porous metal foil has been desired as a current collector for a lithium ion secondary battery, a nickel hydride secondary battery, or a lithium-based polymer secondary battery. For example, there is a punching metal in which a metal plate is perforated by a mechanical method used as a negative electrode current collector of nickel-metal hydride. Is the actual situation. It is said that the thickness of the foil is limited to 40 μm for the stabilization of pores by a mechanical method.
l Not only is it difficult to stabilize the foil by a mechanical method, but it also requires two steps, foil production and drilling, and wastes the metal in the drilled area. There is much room for improvement.

[0005] The present invention has been made based on such knowledge, is capable of stable production, and has a battery (mainly a lithium secondary battery,
The present invention has been devised in order to provide a porous current collector or electrode which is suitable for use in a nickel-metal hydride secondary battery and has excellent economic efficiency. That is, a manufacturing apparatus and a product for obtaining a metal band having a hole area and a total hole area suitable as a battery current collector, and further, by a method such as peeling the plating layer at an appropriate peeling position and peeling angle, It is intended to provide a method and an apparatus for producing a porous metal band capable of continuously producing a long porous metal foil at low cost, or an electrode using the porous metal band as a current collector. Since it cannot be achieved, it is a highly effective and novel technology.

[0006]

In order to achieve the above object, a porous current collector manufacturing apparatus according to the present invention comprises, as a battery current collector, a large number of non-conductive portions having an appropriate area on the surface. This is a device for producing a porous metal strip by depositing a metal on a conductive drum provided so that the total area of the whole becomes an appropriate range, and peeling a plating layer thereof. In the non-conductive part, when a metal band is obtained, stress concentration causes a distortion in the width direction so that distortion does not occur.
Care must be taken to arrange them at the same pitch in the longitudinal direction.

More specifically, there is provided an apparatus for producing a porous metal strip by depositing a metal on a conductive drum provided with a large number of non-conductive portions on its surface and peeling off a plating layer thereof, wherein the apparatus comprises: The area of one of the provided nonconductors is 2.5 *
^10-5 is mm ² ~30mm ^2, and dipping a conductive drum ratio of the total area of the sum and the conductor portion of the area of the non-conductors that are formed on the drum is 0.1 to 9, the drum And a plating bath for plating metal on the drum, and more preferably, a peeling positioning roll for peeling the plating layer from the drum, and a peeling angle adjusting roll for adjusting the peeling angle of the plating layer to be peeled from the drum. , Consisting of

From the viewpoint of stable and continuous production, the above-mentioned manufacturing apparatus is provided with an attached metal removing device for removing the metal attached to the nonconductive portion on the drum. From the viewpoint of preventing corrosion or dirt due to adhesion of liquid residue, the surface of the metal strip may be simply washed with water and dried, but a surface cleaning device for cleaning with a method such as washing with water → pickling → washing with water, and after cleaning the surface. It is preferable to provide a drying device for drying the metal strip.

[0009] Further, when the metal band is such that the average surface roughness (Ra) of the conductor portion of such a device is 0.1 to 3 µm, one of the important characteristics when applied to a current collector. It is preferable from the viewpoint of adhesion to the active material. Ra is 0.1μ
If less than m, the effect of improving the adhesion to the active material is not recognized, and 3
If it exceeds μm, there is a risk of breaking when the plated metal is peeled off, which is not preferable.

The types of metal bands applicable to the porous current collector for batteries include iron, copper, nickel or aluminum, alloys thereof, and multiple layers.

Further, from the viewpoint of simplifying the process and avoiding the risk of breakage of the porous current collector due to tension during winding, the binder is continuously formed on the porous current collector for the battery in the same process as the production of the porous current collector. A stacking device for stacking active materials containing, a drying device for drying the stacked active material, and a press-compression device for pressing the active material onto the current collector after drying and mainly compressing the active material. Is preferred.

[0012] According to a ninth aspect of the present invention, there is provided a method for manufacturing a porous metal strip, comprising: depositing a metal on a conductive drum having a large number of non-conductive portions on its surface; a method of one of the area of the non-conductors provided on the drum a is ^{2.5 * 10 -5 mm 2 ~30mm 2} , and the total sum of the areas of the non-conductors that are formed on the drum A conductive drum having a ratio of 0.1 to 9 to the sum of the areas of the conductors is immersed in a plating bath to form a plating layer on the drum, and a peeling positioning roll is brought into contact with the drum to adjust the metal band. After setting the peeling angle with a peeling angle adjusting roll, the plating layer is peeled from the drum to form a porous metal band, and thereafter, the surface of the metal band is cleaned and the surface-cleaned metal band is dried.

Further, there is a risk that the metal strip may be broken when the metal strip is peeled off depending on the type of the plating metal or the plating thickness. It is preferable to press directly on the plating layer adhering to the substrate.

The cooling roll device may be a roll having merely a surface temperature control function, but it is possible to control the surface temperature by directly contacting the plating layer with a rubber roll and passing cooling water through the rubber roll while contacting the rubber roll. It is preferable that the plating layer is formed of a suitable metal roll, and the surface of the rubber roll is cooled to an appropriate temperature by the metal roll so that the plating layer is uniformly cooled by the elasticity of the rubber.

Further, in the method for manufacturing a battery electrode according to a fourteenth aspect, as described above, the active material containing the binder is continuously laminated on the porous current collector for a battery obtained by the above method. And the step of drying the laminated active material, the step of pressing the laminated active material and the current collector, and the step of mainly compressing the active material to form an electrode are performed in the same process, thereby simplifying the process. It is characterized by avoiding the danger of breaking due to tension during winding and winding of the porous current collector and corrosion during storage of the current collector.

According to a fifteenth aspect of the present invention, the battery electrode is an electrode formed by the manufacturing method of the fourteenth aspect.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the accompanying drawings. In this embodiment, the porous metal band manufactured by the method for manufacturing a porous metal band according to the present invention can be replaced with a copper foil generally used for a negative electrode of a lithium ion secondary battery or a polymer battery. A case of a porous copper foil will be described.

(1) First, as shown in FIGS. 1 to 3, a conductive drum 12 provided with a non-conductor portion 11 in a predetermined pattern on an outer peripheral surface formed of a conductor portion 10 is formed from a copper borofluoride bath in a tank 13. Immersion in a plating bath 14. Here, the conductor portion 10 can be formed of stainless steel, titanium, or the like, and the nonconductor portion 11 is provided in a state where a large number of holes are scattered in the metal, and a synthetic resin piece having high insulating properties is provided in the holes. It can be formed by embedding and making the surface the same flat surface as the conductor portion 10 or slightly increasing the non-conductor portion.

The area of one nonconductive portion 11 is 2.5 * 1
0 ^-5 mm ² and ~30mm ^2, it is essential to a 0.1 to 9 the ratio of the sum of the areas of the total sum and the conductor portion 10 of the area of the non-conductors 11. If the area of one nonconductive portion 11 is less than 2.5 * 10 ^-5 mm ² , it is difficult to continuously obtain a stable hole diameter, and the porosity of the current collector, such as improvement in adhesion, differs greatly depending on the location. .

On the other hand, if it exceeds 30 mm ² , the anchor effect due to the perforation is poor, and the contribution to the improvement of the adhesion is weak. The term “adhesion” as used herein refers to the adhesion between the active material and the current collector, and refers to an effect that the active material is not separated from the current collector due to bending or the like. The reason that the ratio of the sum of the areas of the non-conductor portions 11 to the sum of the areas of the conductor portions 10 is 0.1 to 9 is that if the ratio is less than 0.1, the improvement in adhesion due to the porosity of the current collector is not observed. If the number exceeds 9, the stable peeling from the plating layer drum becomes difficult, and the strength of the current collector is weakened, and there is a danger that breakage occurs frequently between peeling of the plating layer and winding.

The nonconductive portions 11 are circular, elliptical,
Symmetrical shapes such as hexagons and squares are preferable, and the arrangement thereof must be considered to have the same pitch in the width direction and the longitudinal direction so that stress concentration does not occur when a metal band is obtained.
As an example, it is preferable that the circular non-conductive portion having a diameter of 1 mm has a constant pitch interval in the vertical direction and the horizontal direction, or the central portion is the same as the above, but only a few cm outside thereof. It is also preferable that the non-conductive portion having a circular shape having a diameter of 0.1 mm has a constant pitch interval in the vertical and horizontal directions.

On the other hand, the surface roughness of the conductor 10 is preferably 0.1 to 3 μm in order to obtain a rough surface effect. 0.
If the thickness is less than 1 μm, the effect of roughening the adhesion is not recognized. If the thickness exceeds 3 μm, the effect is not only saturated, but also there is a risk that the plating metal is broken when peeled off.

(2) Next, the conductive drum 12 is rotated to form a porous plating layer 15 on the outer peripheral surface of the conductive drum 12. The conductive drum 12 is further rotated to take out the porous plating layer 15 from the plating bath 14 in a state of being adhered to the outer peripheral surface of the conductive drum 12. Here, the thickness of the porous plating layer 15 is generally preferably from 5 to 70 μm in consideration of lightness and economy as a battery current collector. Also,
As the porous plating layer, iron, copper, nickel, aluminum or an alloy thereof, a multi-layered material, or the like is suitably used. In the case of iron, it is preferable to apply nickel plating or the like after peeling since iron is easily rusted.

(3) Immediately after removing the porous plating layer 15 from the plating bath 14, the porous plating layer 15 is cooled using a cooling roll device 16 in order to facilitate peeling. Specifically, as shown in FIGS. 1 and 2, the cooling roll device 16 includes a rubber roll 17 directly in contact with the porous plating layer 15.
And a metal roll 18 which is in contact with the rubber roll 17 and through which cooling water flows. Therefore, first, the porous plating layer 15 is uniformly cooled by the rubber roll 17 whose surface is cooled by the metal roll 18 by utilizing the elasticity of rubber, and by utilizing the difference in the expansion coefficient due to the temperature difference from the drum surface, Subsequent peeling can be facilitated.

Further, the plating layer 15 can be cooled via the cooled metal roll 18 and the rubber roll 17 instead of directly cooling the cooling water onto the porous plating layer 15 and cooling. Since there is no danger of falling into the bath 14 and the safety of the work and the change of the plating bath concentration can be prevented, the target porous metal strip can be stably manufactured.

It is also preferable to provide a scraping jig A in contact with the conductive drum 12 in order to prevent foreign substances such as plating sludge in the plating bath from adhering to the drum and the porous plating layer. Naturally, it is necessary to provide a sticky rubber roll, a tray, or the like so as to prevent the adhered substance scraped off from re-adhering or entering the plating bath to remove foreign matter.

In order to obtain a porous current collector stably, it is important to remove as much as possible the adhering substance which causes a defective shape of the hole and breaks when the plating layer is peeled off.

(4) After the porous plating layer 15 is cooled by the cooling roll device 16, a peeling positioning roll 19 disposed on the outer surface of the conductive drum 12 and at a predetermined distance from the cooling roll device 16, and The conductive drum 12 is separated via a pair of peeling angle adjusting rolls 20 and 21 disposed in the space at a predetermined distance from the peeling positioning roll 19.
From the outer peripheral surface as a porous metal band 15a as shown in FIG.

Here, as shown in FIG. 2, an appropriate peeling position P of the peeling positioning roll 19, a tangent line L1 at the peeling position P, an outer peripheral surface of the peeling positioning roll 19 and a pair of peeling angle adjusting rolls 20, The proper peeling angle θ formed by the peeling line L2 connecting to the clamping surface of the plating bath 21 is
4 is experimentally determined by the contents of the plating solution, the hole shape and the total hole area, and the thickness of the metal foil.

Therefore, the porous plating layer 15 can be peeled at the peeling position P and the peeling angle θ that are most suitable for the characteristics, and the porous metal band 15a can be peeled as a long object without breaking. . Although not particularly shown in the figure, a large amount of the plating solution adhering to the stripped metal strip is almost removed by a ringer roll or the like before entering the surface cleaning apparatus, and each tank of the surface cleaning apparatus is removed. It is needless to say that it is preferable to provide a ringer roll or the like on the outlet side to almost remove the adhering liquid.

(5) Next, as shown in FIG. 1, the surface of the porous metal band 15a is passed through the water 25 filled in the water tank 24 having the reversing roll 23 via the reversing roll 22. To perform a surface cleaning treatment. The surface cleaning treatment mentioned here includes not only washing with water but also a combined treatment such as washing with water, pickling, and washing with water, and refers to removing a plating solution residue attached to a plating layer.

In the surface cleaning treatment, it is only necessary to wash and dry after peeling off the plating layer. More preferably, in order to almost completely remove the plating solution residue adhering to the plating layer, after washing with water, acidify with dilute sulfuric acid or the like. It is desirable to wash and then wash with water. For example, when obtaining a porous current collector in a copper borofluoride bath,
Simply washing with water may leave brown spots on the plated surface after only one day at room temperature. It is considered that the reason for this is that fluorine in the plating solution residue, which could not be sufficiently removed by water washing, reacts with moisture in the air to form highly corrosive HF, and locally corroded copper. As a result, such spots do not occur.

(6) As shown in FIG. 1, after washing, the porous metal band 15a to be a porous current collector is dried by the first drying device 27 via the reversing roll 26, and then the binder and graphite are removed. After immersing the mixed active material 28 in the active material tank 29,
Excess active material is removed with a knife coater so as to have a predetermined thickness, and laminated on both sides of the porous metal strip 15a to produce a laminated porous metal strip 15b.

(7) After drying the laminated porous metal band 15b by the second drying device 30, the pressure-compression roll 31
Then, the active material 28 is compressed at a compression ratio of about 50% by using, and wound on a reel 33 as a battery electrode 32.

In the same step, when the porous current collector and the active material are laminated and then pressed and compressed, the following advantages are obtained.・ Simplification of process and improvement of economy. -Since the active material is applied under conditions that hardly cause surface oxidation or corrosion of the porous metal strip, an electrode having a more stabilized porous current collector can be manufactured. -To properly wind the porous current collector, it is necessary to apply some tension.There is a risk that the porous current collector, which originally has low strength, may break, but the electrode obtained by laminating and pressing the active material has a low strength. It becomes strong and does not break even when tension is applied,
It becomes possible to wind up stably and neatly.

(8) After this battery electrode 32 is cut into an appropriate size, it is preferably used as a negative electrode 37 of a card-shaped lithium polymer battery 34 expected to grow rapidly in the future, for example, as shown in FIG. Can be used. FIG.
In 36, 36 denotes a gel-like polymer electrolyte,
Reference numeral 5 denotes a positive electrode using an active material mainly composed of lithium nickelate, 38 denotes an exterior material made of a composite foil,
Numeral 40 indicates a lead wire. Further, the present invention is also applicable to lithium ion secondary batteries and the like which are widely available on the market.

[0037]

As described above, according to the apparatus of the present invention, the individual area and the total area of the non-conductive portion of the plating drum, which has a great influence on the characteristics and production of the porous metal strip, and the surface roughness of the conductive portion. Focusing on the current collector for batteries, the development has been carried out, so that it is possible to economically obtain a porous metal band (current collector) with good adhesion to the active material, which is an important characteristic of the current collector Became possible. Further, since the porous plating layer is peeled off from the outer peripheral surface of the conductive drum via a peeling positioning roll and a pair of peeling angle adjusting rolls, and then washed to produce a porous metal band, the porous plating layer, Peeling can be performed at a peeling position and a peeling angle most suitable for the characteristics, and the porous metal strip can be peeled as a long object without breaking.

In the method for manufacturing a porous current collector according to the present invention, the plating layer is cooled by directly pressing the cooling roll device against the plating layer adhered to the outer peripheral surface of the conductive drum. Can be easily performed, cooling water can be reliably prevented from dropping into the plating bath, and a porous metal strip serving as a porous current collector can be stably manufactured.

In the production method of the present invention, the cooling roll device cools the plating layer from the water-cooled metal roll via the rubber roll, so that the plating layer can be cooled uniformly by the elasticity of the rubber. Even when water accidentally leaks from the metal roll, the cooling water can be reliably prevented from dropping into the plating bath, so that the porous metal strip can be manufactured more stably.

In the present invention, a porous metal strip can be manufactured at low cost by using copper, nickel, aluminum, or the like as a plating metal for a plating bath.

[Brief description of the drawings]

FIG. 1 is a block diagram showing steps of a method for manufacturing a porous metal strip according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement relationship of a peeling positioning roll and a peeling angle adjusting roll with respect to a conductive drum.

FIG. 3 is a perspective view of a conductive drum.

FIG. 4 is a perspective view of a porous metal strip.

FIG. 5 is a plan view of a polymer battery using a porous metal band as a negative electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Conductor part 11 ... Non-conductive part 12 ... Conductive drum 14 ... Plating bath 15 ... Porous plating layer 15a ... Porous metal band 15b ... Laminated porous metal band 19 ... -Peeling positioning roll 20 ... Peeling angle adjusting roll 21 ... Peeling angle adjusting roll

Claims (15)

[Claims] An apparatus for producing a metal strip having a large number of holes by depositing a metal on a conductive drum provided with a large number of non-conductive portions on a surface thereof and peeling a plating layer of the metal. The area of one of the non-conductive parts provided on the drum is 2.5 *
^10-5 is mm ² ~30mm ^2, and the ratio is 0.1 to 9 drum with the total sum of the areas of the sum and the conductor portion of the area of the non-conductors that are formed on the drum, rotates continuously The method for manufacturing a porous current collector for a battery according to claim 1, wherein the metal is plated on the conductor portion, and then the plated metal is peeled off to form a porous current collector. 2. A plating bath for dipping the drum and plating a metal on the drum, a peeling positioning roll for peeling a plating layer from the drum, and a peeling angle of the plating layer peeling from the drum. 2. The apparatus according to claim 1, further comprising a peeling angle adjusting roll for adjusting. 3. A post-process of the peeling angle adjusting roll, wherein a surface cleaning device for cleaning the surface of the metal band and a drying device for drying the metal band after the surface cleaning are provided. 3. The device according to 1 or 2. 4. The apparatus according to claim 1, wherein the conductor has an average surface roughness (Ra) of 0.1 to 3 μm. 5. The apparatus according to claim 1, further comprising an attached metal removing device provided on said drum for removing metal attached to said non-conductive portion. 6. The device according to claim 1, wherein the metal strip is iron, copper, nickel or aluminum. 7. A cooling roll device capable of rapidly and preferentially cooling the plating layer on the drum coming out of the plating bath so as to facilitate the peeling of the plating layer from the drum. The apparatus according to any one of claims 1 to 6. 8. A laminating apparatus for continuously laminating an active material containing a binder on a porous current collector obtained by the apparatus according to any one of claims 1 to 6, and An electrode manufacturing apparatus for a battery, comprising: a drying device for drying; and a compression / compression device for pressing an active material onto a porous current collector after drying and compressing the active material to form an electrode. 9. A method for producing a metal strip having a large number of holes by depositing a metal on a conductive drum provided with a large number of non-conductive portions on a surface thereof and peeling off a plating layer thereof. The area of one of the non-conductive parts provided on the drum is 2.5 *
^10-5 is mm ² ~30mm ^2, and dipping the ratio of the total area of the sum and the conductor portion of the area of the non-conductors formed on the drum in a plating bath of conductive drum is 0.1 to 9 Then, a plating layer is formed on the drum, a peeling positioning roll is brought into contact with the drum, and an appropriate peeling angle of the metal band is set with a peeling angle adjusting roll. Then, the plating layer is peeled from the drum to form a porous metal band. And thereafter, cleaning the surface of the metal band and drying the surface-cleaned metal band. 10. The manufacturing method according to claim 9, wherein the stripping of the metal band is performed by directly pressing a cooling roll device against the plating layer attached to the outer peripheral surface of the drum. 11. The cooling roll device is formed of a rubber roll that is in direct contact with the plating layer, and a metal roll that is in contact with the rubber roll and whose temperature can be adjusted by, for example, passing cooling water through the rubber roll. The method according to claim 10, wherein the plating layer is cooled by cooling the surface of the rubber roll to an appropriate temperature with the metal roll. 12. The method according to claim 9, wherein the metal strip is made of iron, copper, nickel, or aluminum. 13. A porous current collector for a battery manufactured by the manufacturing method according to claim 9. 14. An active material containing a binder is successively laminated on the porous current collector for a battery obtained in claim 13, the laminated active material is dried, and the laminated active material and the current collector are collected. A method for producing an electrode for a battery, comprising compressing and compressing a body in one step to produce an electrode. 15. An electrode for a battery formed by the method according to claim 14.