JP3429448B2 - Battery porous current collector, electrode, method and apparatus for producing them - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a porous current collector for a battery, which is 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 them. Regarding

[0002]

2. Description of the Related Art Conventionally, as a method for producing a metal mesh foil from a plating bath, many patents have been issued, such as plating a conductive drum provided with a non-conductive portion and peeling it off. From this viewpoint, This is a known fact. As an example of a recent patent, there is a method presented in Japanese Patent Laid-Open No. 8-100288. In this manufacturing method, a plating layer is formed by electroplating on a metal drum in which an insulating material is embedded in a predetermined pattern on the outer peripheral surface, and the plating layer is extended from the plating solution into the air to the peeling interface. The range is 0 ℃ to 15 ℃
It is characterized in that the plating layer and the surface are washed with cold water. In addition, as an effect brought about 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 embedded insulating material does not fall off from the metal drum. It is described that a long and inexpensive metal mesh foil can be continuously manufactured.

[0003]

However, the above-mentioned method for producing a metal mesh foil still has the following problems to be solved. That is, according to the research conducted by the present inventor, the metal mesh foil manufactured using the same manufacturing method is extremely thin and porous, and therefore, when peeled at an appropriate peeling position or a peeling angle other than the peeling angle, for example, the preceding step Even if it is cooled with, the foil often breaks and stable production is difficult. Further, this method is not practical because the cooling water falls into the plating tank and the concentration of the plating solution decreases, and the intended 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 hydrogen secondary battery, a lithium polymer secondary battery, or the like. For the porosity of the metal plate, for example, there is a punching metal in which a hole is made in the metal plate by a mechanical method used as a negative electrode collector of nickel hydrogen, but it is not possible to meet the recent demand for thin plate porosity. Is the reality. It is said that the limit of the stable porosity by mechanical method is the foil thickness of 40 μm. Currently used Cu foil of 20 μm or less or A
l It is not only difficult to stabilize the porosity of the foil by a mechanical method, it also requires two steps of manufacturing the foil and making holes, and the metal in the holes is wasted. However, there is much room for improvement.

The present invention has been made on the basis of such knowledge and enables stable production, and batteries (mainly lithium secondary batteries,
It was devised in order to provide a highly economical porous current collector or electrode suitable for a nickel-hydrogen secondary battery). That is, a manufacturing apparatus and a product for obtaining a metal strip having a hole area and a total hole area suitable as a current collector for a battery, and further by a method such as peeling a plating layer at a proper peeling position and a peeling angle. A porous metal strip capable of continuously producing a long porous metal foil at a low cost, or a method and an apparatus for producing an electrode using the porous metal strip as a current collector are provided. It is a highly effective and novel technology because it cannot be achieved.

[0006]

In order to achieve the above-mentioned object, the porous current collector manufacturing apparatus of the present invention has a large number of non-conducting portions on the surface of a non-conducting portion as a current collector for a battery. This is an apparatus for producing a porous metal band by depositing a metal on a conductive drum provided so that the total area of the whole is within an appropriate range and peeling off the plating layer. When the metal strip is obtained in the non-conductor part, the stress concentration causes the distortion in the width direction,
It must be taken into consideration that they are arranged at the same pitch in the longitudinal direction.

More specifically, it is an apparatus for producing a porous metal strip by depositing a metal on a conductive drum having a large number of non-conductive parts on its surface and peeling off the plating layer thereof, which is provided on the drum. The area of one of the non-conductive parts provided 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 the metal on the drum, 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 peeled from the drum. Consists of.

From the viewpoint of stable continuous production, the above-mentioned manufacturing apparatus is provided with an adhering metal removing device for removing the metal adhering to the non-conductor portion on the drum, and further, in the subsequent step of the peeling angle adjusting roll, plating From the viewpoint of preventing corrosion or dirt due to liquid residue adhesion, the surface of the metal strip may be simply washed with water → dried, but with a surface cleaning device for cleaning by such methods as water cleaning → pickling → water cleaning, and after surface cleaning It is preferable to provide a drying device for drying the metal strip.

Further, when the average surface roughness (Ra) of the conductor portion of such a device is 0.1 to 3 μm as a metal band, 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 it is 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.

Examples of the type of metal strip applicable to the porous current collector for batteries include iron, copper, nickel or aluminum, their alloys, and multiple layers.

Further, from the viewpoint of simplifying the process and avoiding the risk of breaking the porous current collector due to tension during winding, the binder is continuously applied onto the porous current collector for a battery in the same process as in the production of the porous current collector. A stacking device for stacking the active material containing the above, a drying device for drying the stacked active material, and a compression and compression device for compressing the active material to the current collector after drying and mainly compressing the active material are provided. Is preferred.

The preparation method of the porous metal strip according to claim 8, a number of non-conductor section metal to precipitate on the conductive drum provided on the surface, and peeled off the plating layer, forming a number of holes The method for manufacturing a metal strip according to claim 1, wherein the area of one of the non-conductor portions provided on the drum is 2.5 * 10 ⁻⁵ mm.
² ～30Mm is ² and the ratio of the total area of the sum and the conductor portion of the area of the non-conductors formed on the drum 0.
By immersing the a 1-9 conductive drum plating bath to form a plating layer on the <br/> drum, a proper peel angle of the metal strip is brought into contact with the peeling positioning rolls on the drum at a peel angle adjustment roll after setting, by peeling the plated layer from the drum to form a porous metal strip, after which the surface of the metal strip is cleaned, characterized by drying the metal strip and surface cleaning.

Further, depending on the type of plating metal and the plating thickness, there is a risk of breaking the metal strip when it is peeled off. In order to peel the metal strip from the drum more easily and stably, the cooling roll device is attached to the outer peripheral surface of the drum. It is preferable to directly press against the plating layer attached to.

The cooling roll device may be a roll simply having a surface temperature adjusting function, but it is possible to adjust the surface temperature such as a rubber roll which is in direct contact with the plating layer and a rubber roll which is in contact with the rubber roll and through which cooling water is passed inside. It is preferable that the plating layer is formed of a different metal roll, and the surface of the rubber roll is cooled to an appropriate temperature by the metal roll to uniformly cool the plating layer due to the elasticity of the rubber.

Further, in the method for producing a battery electrode according to claim 13 , as described above, the active material containing a binder is subsequently laminated on the porous battery current collector obtained by the above method. The steps of drying the laminated active material, pressing the laminated active material and the current collector, and mainly compressing the active material to form an electrode in the same step. The present invention is characterized by avoiding the risk of breakage due to tension during winding of the porous collector and the current collector and corrosion during storage of the collector.

The battery electrode according to claim 14 is the following:
13 is an electrode formed by the manufacturing method of 13 .

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to an embodiment shown in the accompanying drawings. In this embodiment, the porous metal strip manufactured by the method for producing a porous metal strip 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. An explanation will be given by taking up the case of a porous copper foil.

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

The area of one non-conductor 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 non-conductor portion 11 is less than 2.5 * 10 ⁻⁵ mm ² , it is difficult to obtain a continuous and stable pore size, and the porosity effect of the current collector, such as the improvement of adhesion, greatly differs depending on the location. .

On the other hand, when it exceeds 30 mm ² , the anchor effect due to the opening of holes is poor and the contribution to the improvement of adhesion is weakened. The term "adhesion" as used herein refers to the adhesion between the active material and the current collector, and the effect that the active material is not separated from the current collector due to bending or the like. In addition, the reason why the ratio of the total area of the non-conductive portion 11 to the total area of the conductive portion 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 it exceeds 9, it is not only difficult to stably peel from the plating layer drum, but also the strength of the current collector is weakened, and there is a risk of frequent breakage between peeling of the plating layer and winding.

The non-conductor portions 11 are circular, oval, and
A symmetric shape such as a hexagon or a quadrangle is preferable, and it is necessary to consider that the arrangement has the same pitch in the width direction and the longitudinal direction so that stress concentration does not occur when a metal strip is obtained.
As an example, it is preferable that the circular non-conductor part having a diameter of 1 mm has a constant pitch interval in the vertical direction and the horizontal direction, or the center part is the same as the above, but only a few cm outside thereof. It is also preferable that the circular non-conductor parts having a diameter of 0.1 mm have a constant pitch interval in the vertical direction and a constant pitch interval in the horizontal direction.

On the other hand, the surface roughness of the conductor portion 10 is preferably 0.1 to 3 μm in order to obtain the roughening effect. 0.
If it is less than 1 μm, the effect of roughening the adhesion is not observed, and if it exceeds 3 μm, the effect is not only saturated, but there is a risk of breaking when the plated metal is peeled off.

(2) Next, the conductive drum 12 is rotated to form the 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 attached to the outer peripheral surface of the conductive drum 12. Here, the thickness of the porous plating layer 15 is generally preferably 5 to 70 μm in consideration of lightness and economy as a current collector for a battery. Also,
As the porous plating layer, iron, copper, nickel, aluminum or an alloy thereof, a multi-layered product or the like is preferably used. However, in the case of iron, it is preferable to apply nickel plating or the like after peeling since it is easily rusted.

(3) Immediately after taking out 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 that is in direct 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 is passed. Therefore, first, by the rubber roll 17 whose surface is cooled by the metal roll 18, the porous plating layer 15 is uniformly cooled by utilizing the elasticity of rubber, and by utilizing the difference in expansion coefficient due to the temperature difference from the drum surface, The subsequent peeling can be facilitated.

Further, since the cooling water is not directly applied to the porous plating layer 15 to cool it, the plating layer 15 can be cooled via the cooled metal roll 18 and the rubber roll 17, so that the cooling water is plated. Since there is no danger of dropping into the bath 14 and it is possible to prevent work safety and to prevent changes in the concentration of the plating bath, it is possible to stably manufacture the desired porous metal strip.

Further, in order to prevent foreign matters such as plating sludge in the plating bath from adhering to the drum and the porous plating layer, it is preferable to provide a scraping jig A in contact with the conductive drum 12. As a matter of course, the adhered substance scraped off needs to be provided with a rubber roll or a saucer having an adhesive property so as to prevent the adhered substance from re-adhering or entering the plating bath to remove the foreign matter.

In order to obtain a porous current collector in a stable manner, it is important to remove as much as possible the adhered substances that cause pore shape defects and breakage when the plating layer is peeled off.

(4) After the porous plating layer 15 is cooled by the cooling roll device 16, the peeling positioning roll 19 is provided on the outer surface of the conductive drum 12 at a position separated from the cooling roll device 16 by a predetermined distance, and The conductive drum 12 is provided via a pair of peeling angle adjusting rolls 20 and 21 which are spaced apart from the peeling positioning roll 19 by a predetermined distance.
The porous metal strip 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 the clamp surface of 21 is the plating bath 1
It will be experimentally determined by the content of the plating solution in 4, the hole shape, 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 which are most suitable for the characteristics, and the porous metal band 15a can be peeled as a long product without breaking. . Although not particularly shown in the figure, most of the plating solution adhered to the peeled metal strip is removed by a ringer roll before entering the surface cleaning device, and each tank of the surface cleaning device is removed. It is needless to say that it is preferable that a ringer roll or the like is also provided on the outlet side of the to remove almost all the adhering liquid.

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

The surface cleaning treatment may be performed simply by washing with water after peeling off the plating layer and then drying. More preferably, in order to almost completely remove the residue of the plating solution adhering to the plating layer, after washing with water, acid treatment with dilute sulfuric acid or the like is carried out. It is desirable to wash and then wash with water. For example, when obtaining a porous current collector in a copper borofluoride bath,
With just washing with water, dark spots may appear on the plated surface if it is left at room temperature for one day. It is considered that the cause of this is that the fluorine in the residue of the plating solution, which could not be sufficiently removed by washing with water, reacts with the moisture in the air to form HF, which is highly corrosive, and locally corroded copper. As a result, such spots do not occur.

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

(7) The laminated porous metal strip 15b is dried by the second drying device 30, and then the compression compression roll 31 is used.
After compressing the active material 28 with a compression ratio of about 50%, it is wound on the reel 33 as the battery electrode 32.

When the porous current collector and the active material are laminated in the same step and then compression-compressed, the following merits occur.・ Simplified process and improved economy. Since the active material is applied under the condition that surface oxidation or corrosion of the porous metal strip hardly occurs, it is possible to manufacture an electrode having a more stable porous current collector.・ To properly wind up the porous current collector, it is necessary to apply tension to some extent, and there is a risk that the porous current collector, which is originally low in strength, will break, but the electrode obtained by laminating and pressing the active material has low strength. It becomes stronger and does not break even if tension is applied,
You will be able to wind up stably and cleanly.

(8) After being cut to an appropriate size, the battery electrode 32 is preferably used as the negative electrode 37 of a card-shaped lithium polymer battery 34 which is expected to grow rapidly in the future as shown in FIG. 5, for example. Can be used. Note that FIG.
In the figure, 36 indicates a gel-like polymer electrolyte substance, and 3
5 indicates a positive electrode using an active material mainly composed of lithium nickel oxide, 38 indicates an exterior material made of a composite foil, 39,
40 indicates a lead wire. It can also be applied to lithium-ion secondary batteries and the like that are widely available on the market.

[0037]

As described above, in the apparatus of the present invention, the individual area and the total area of the non-conductor 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 conductor portion. Since the development was focused on the current collector for batteries, economically obtaining a porous metal band (current collector) with good adhesion to the active material, which is an important property of the current collector. Became possible. Further, since the porous plating layer is peeled from the outer peripheral surface of the conductive drum via a peeling positioning roll and a pair of peeling angle adjusting rolls, and then the porous metal strip is manufactured by washing, thus forming the porous plating layer, Peeling can be performed at a peeling position and a peeling angle most suitable for the characteristics, and a long product can be peeled without breaking the porous metal band.

In the method for producing a porous current collector of the present invention, the plating layer is peeled off by cooling the plating layer by directly pressing the cooling roll device against the plating layer attached to the outer peripheral surface of the conductive drum. It is possible to easily prevent the cooling water from falling into the plating bath, and it is possible to stably manufacture the porous metal strip to be the porous current collector.

Further, in the manufacturing method of the present invention, since the cooling roll device cools the plating layer from the water-cooled metal roll through the rubber roll, the elasticity of the rubber can uniformly cool the plating layer, and Even if water accidentally leaks from the metal roll, the cooling water can be surely prevented from falling into the plating bath, so that the porous metal strip can be manufactured more stably.

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

[Brief description of 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 a positional relationship between 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 band.

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

[Explanation of symbols]

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

Continuation of the front page (56) Reference JP-A-63-128192 (JP, A) JP-A-62-205296 (JP, A) JP-A-54-62128 (JP, A) JP-A-51-110444 (JP , A) JP-A-10-195689 (JP, A) JP-A-8-236120 (JP, A) JP-A-8-100288 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) C25D 1/20 C25D 1/08 H01M 4/04 H01M 4/64

Claims (14)

(57) [Claims] 1. A large number of non-conductor portion by depositing a metal on the conductive drum provided on the surface, and peeled off the plating layer, there is provided an apparatus for producing a metal strip formed with many holes, the Do
Ram, is one of the area is 2.5 * 10 ^-5 mm ² ~30mm ² nonconductor portion provided thereon, and the sum and the conductor portion of the area of the non-conductors formed on the drum The ratio of the area to the total area is 0.1 to 9, and the drum is continuously rotated to plate the conductor with metal.
Plating bath and the peeling position for peeling the plated metal on the drum.
Adjust the peeling angle between the coating roll and the plating layer peeled from the drum
An apparatus for manufacturing a porous current collector for a battery , which is provided with a peeling angle adjusting roll, for forming a porous current collector. 2. A surface cleaning device for cleaning the surface of the metal strip and a drying device for drying the metal strip after the surface cleaning are provided in the subsequent step of the peeling angle adjusting roll. 1. The device according to 1 . 3. The average surface roughness (Ra) of the conductor portion is 0.
The device according to claim 1 or 2 having a size of 1 to 3 µm. To wherein said drum apparatus according to any one of claims 1 to 3 provided the deposited metal removing device for removing metal adhered to the non-conductors. Wherein said metal band, iron, copper, apparatus according to any one of claims 1 to 4, which is a nickel or aluminum. 6. A cooling roll device capable of preferentially and rapidly cooling the plating layer on the drum which has come out of the plating bath in order to facilitate the peeling of the plating layer from the drum. The device according to any one of 1 to 5 . 7. A stacking device for successively stacking an active material containing a binder on the porous current collector obtained by the device according to any one of claims 1 to 6, and the stacked active material. An electrode manufacturing apparatus for a battery, comprising: a drying device for drying; and a compression / compression device for compressing the active material onto the porous current collector after drying and mainly compressing the active material to form an electrode. 8. A method for producing a metal strip having a large number of holes by depositing a metal on a conductive drum having a large number of non-conductive portions on the surface and peeling off the plated layer. The area of one non-conductor part on the drum is 2.5 * 1
0 ^-5 mm ² is ~30mm ^2, and the conductive drum ratio is 0.1 to 9 and sum of the areas of the sum and the conductor portion of the area of the non-conductors formed on the drum plating bath immersed to form a plating layer on the drum, after setting the proper peel angle of the metal strip is brought into contact with the peeling positioning rolls on the drum at a peel angle adjustment roll, by peeling the plating layer from said drum perforated metal to form a band, then the surface of the metal strip is cleaned, the production method of the porous metal strip, characterized in that drying the metal strip and surface cleaning. 9. The method of claim 8, characterized in that when separation of the metal strip, by pressing a cooling roll device directly to the plated layer which adheres to the outer peripheral surface of the drum
The manufacturing method described. 10. The cooling roll device comprises a rubber roll which is in direct contact with the plating layer and a metal roll which is in contact with the rubber roll and whose temperature can be adjusted by a method such as passing cooling water inside. The plating layer is cooled by cooling the surface of the rubber roll to an appropriate temperature with the metal roll.
9. The manufacturing method according to 9 . 11. The process according to the metal band, iron, copper, any of claims 8-10 is nickel or aluminum. 12. A porous current collector for a battery, which is manufactured by the manufacturing method according to any one of claims 8 to 11 . 13. The active material containing a binder is subsequently laminated on the porous current collector for battery obtained in claim 12 , and the laminated active material is dried to form a laminated active material and a current collector. A method of manufacturing an electrode for a battery, which comprises pressing and compressing a body in one step to manufacture an electrode. 14. A battery electrode formed by the method of claim 13 .