JP2011198765A - Metal foil sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal foil sheet having a continuous pattern seamless in the longitudinal direction, which is preferably used in a collector for a secondary battery.SOLUTION: A coiled metal foil sheet has through-holes of prescribed shapes regularly arranged at prescribed intervals, an etched pattern continuing seamlessly, and a raw portion continuing in a belt shape in the longitudinal direction, and either one of a positioning hole, a conveying hole, and a detection mark is formed in the raw portion, and the metal foil sheet is used in the collector for the secondary battery.

Description

  The present invention relates to a metal foil sheet mainly used for a current collector for a secondary battery.

  Since polymer batteries can be made thinner and lighter, they are widely studied and used in part for power supplies associated with the development of portable electronic devices. The polymer battery, which is currently in practical use, has a positive electrode plate with a lithium salt that acts as a positive electrode active material supported on an aluminum current collector, and a carbon that acts as a negative electrode active material on a copper current collector. An electrolyte material (for example, a gel electrolyte polymer or a solid electrolyte) is sandwiched between the negative electrode plate.

  Among the electrolyte materials used, the gel electrolyte polymer contains a solvent so that it can be easily applied onto the positive electrode plate or the negative electrode plate (hereinafter referred to as “electrode plate”). There is. Thus, in the electrolyte material containing a solvent, it is necessary to volatilize the contained solvent after the electrolyte material is configured to be sandwiched between electrode plates. Therefore, conventionally, the current collector constituting the electrode plate has been provided with a pattern (pattern) in which relatively small through holes are regularly arranged so that the solvent is easily volatilized.

  Such a current collector is manufactured by lathing a metal foil sheet. The lath processing is a processing method in which a number of cuts in a certain direction are provided in the metal foil sheet, and the cut portions are formed into a lath shape by pulling in a direction perpendicular to the cut direction, and then pressed. The metal foil sheet for a current collector manufactured by this method can be continuously provided with a pattern in which through holes are arranged by a simple method, and is supplied at a low cost.

  However, the metal foil sheet subjected to lath processing has a problem that the pattern in which the through holes are arranged is not constant and the dimensional accuracy is inferior. When such a metal foil sheet is used for a current collector constituting an electrode plate, charging or discharging between the electrode plate and the electrolyte material is not uniformly performed in each part, so that a polymer battery having high battery performance is obtained. Cause problems that can not be.

  On the other hand, in the production process of the polymer battery, it is required to further improve the productivity of the polymer battery by improving the efficiency of the process of cutting the metal foil sheet into a current collector. One of these requirements is to make it easier to feed and position the metal foil sheet, and to carry out each process by reel-to-reel hoop transport, so that it is continuous in a strip shape in the longitudinal direction. There is a demand for supplying a metal foil sheet having an unprocessed portion. However, it is difficult to provide an unprocessed portion on the metal foil sheet by the above-described lath processing because of its manufacturing method, and the above request cannot be achieved. That is, the lath processing is a method of uniformly cutting and pulling the metal foil sheet, so that it is difficult to provide an unprocessed portion that does not have a cut, and it is possible to improve the dimensional accuracy including the unprocessed portion. There is a problem that you can not.

  Therefore, based on the most demanding demand in the market for (a) that the array of through holes are continuously processed with high precision and (b) high performance and low price, the metal foil sheet is inexpensive. And (c) to improve the efficiency of the processing process of the metal foil sheet, and to supply in a state having unprocessed portions that are continuous in a strip shape in the longitudinal direction of the metal foil sheet.

  For such a demand, it is conceivable to apply a method using photolithography. This method is a method comprising, in order of process, a photosensitive resist coating process on a material to be processed, a contact exposure process using a photomask having a predetermined pattern, a developing process, an etching process, and a resist stripping process. If a metal foil sheet is manufactured by this method, it is possible to form an array pattern of through holes and a continuous unprocessed portion that are accurately processed in the metal foil sheet, but the size is limited. Since the photomask is moved intermittently to expose the etching pattern, it is considered that a seam is formed, the pattern is likely to be discontinuous, and the productivity is remarkably lowered.

  In addition, a method of providing an array pattern of through-holes in the metal foil sheet by applying mechanical punching may be considered, but the obtained metal foil sheet may have processing distortion and burrs, and productivity. However, there is a difficulty in this point, and it can be considered that the problem becomes expensive.

  The present invention has been accomplished in view of the above-mentioned present situation, and the object thereof is to have a seamless pattern in the longitudinal direction, which is preferably used mainly for a current collector for a secondary battery such as a polymer battery. It is in a metal foil sheet.

  The metal foil sheet of the present invention for solving the above-mentioned problem is that a through hole having a predetermined shape is regularly arranged at regular intervals, a continuous etching pattern without a seam, and a non-processed part continuous in a strip shape in the longitudinal direction. In the unprocessed portion, any one of a positioning hole, a transport hole, and a detection mark is provided, and is used as a current collector for a secondary battery.

  In addition, the metal foil sheet of the present invention for solving the above-mentioned problem is that the through-holes of a predetermined shape are regularly arranged at regular intervals, a continuous etching pattern without a seam, and a non-processed continuous belt in the longitudinal direction And the etching pattern is a pattern formed by single-sided etching, and is used as a current collector for a secondary battery.

  In addition, the metal foil sheet of the present invention for solving the above-mentioned problem is that the through-holes of a predetermined shape are regularly arranged at regular intervals, a continuous etching pattern without a seam, and a non-processed continuous belt in the longitudinal direction And the area of the opening portion on the front surface side of the through hole is larger than the area of the opening portion on the back surface side of the through hole, and is used as a current collector for a secondary battery. .

  Such a metal foil sheet is preferably used for a current collector for a secondary battery. The metal foil sheet is cut into a predetermined size as necessary and processed into a secondary battery current collector to constitute a part of the secondary battery. A current collector for a secondary battery to which the metal foil sheet of the present invention is applied is a solvent contained in an electrolyte material containing a solvent, for example, a gel electrolyte polymer containing a solvent, particularly in the production process of the secondary battery. It works effectively to volatilize.

  Further, the manufacturing method of one embodiment of the metal foil sheet is a method of manufacturing a metal foil sheet having a seamless etching pattern, and a resist ink is pattern-printed on the surface of the metal foil sheet by rotary printing. It has the characteristics of having a process, the process of etching the surface of the said metal foil sheet original fabric by which pattern printing was carried out, and the process of removing the said resist ink. According to the present invention, since the resist ink is printed or applied in a pattern by rotary printing, a resist ink coating portion (hereinafter referred to as “non-etched portion”) that is not etched can be provided seamlessly. As a result, a portion that is not covered with the resist ink (hereinafter referred to as an “etching portion”) can be formed into a continuous pattern by performing an etching process thereafter. Finally, the resist ink is removed to produce a metal foil sheet having a seamless etching pattern. In addition, since the continuous pattern is formed by etching, the dimensional accuracy is superior to that of the machined one, and there is no processing distortion or burr. As a result, when used as a current collector for a secondary battery, charging and discharging between the electrode plate made of the current collector and the electrolyte material can be made uniform.

  In this manufacturing method, the metal foil sheet which further has the unprocessed part which continues in strip | belt shape in a longitudinal direction can be manufactured preferably. According to the present invention, the resist ink can be easily coated by rotary printing on the portion where a continuous unprocessed portion in the longitudinal direction is to be formed. Therefore, the resist ink coating portion is not formed by the subsequent etching process. It can be easily left in the processed state.

  Moreover, in the manufacturing method of one Embodiment of a metal foil sheet, the said etching process is a single-sided etching process, and before the said etching process, the said pattern printed surface (henceforth "etching process surface"). A metal foil sheet can be produced by a method further comprising a step of providing an etching mask over the entire back surface of the substrate and a step of removing the etching mask after the step of etching. According to the present invention, since single-sided etching is performed, a difficult process of accurately aligning the printed pattern of the resist ink on the front and back surfaces is eliminated as in double-sided etching. Further, since the etching mask is provided on the entire back surface of the etching processing surface, the back surface is not etched even by etching, and an etching pattern can be formed with high accuracy. Furthermore, as described above, since the metal foil sheet used for the current collector for the secondary battery is relatively thin, the metal foil sheet is not thick enough to reduce the etching speed even by single-sided etching. Production efficiency is not reduced so much.

  When the metal foil sheet obtained by the method for producing the metal foil sheet is used as a current collector for a secondary battery, the current collector is provided with a continuous pattern regardless of which part of the metal foil sheet is used. Can do. As a result, it is possible to efficiently perform the manufacturing process of processing into a current collector for a secondary battery, and to contribute to the efficiency of manufacturing a high-performance and inexpensive secondary battery. This contributes to the market demand for supplying secondary batteries to the market.

  As described above, according to the metal foil sheet of the present invention, it has a seamless continuous etching pattern, and the current collector obtained from the metal foil sheet has excellent dimensional accuracy in any part. Since the same continuous pattern is used, the solvent contained in the electrolyte material can be removed by volatilization uniformly, and charging and discharging between the current collector electrode plate and the electrolyte material can be made uniform. This can contribute to improvement and stabilization of the manufactured secondary battery. Moreover, since it has the unprocessed part which continues in strip | belt shape in a longitudinal direction, it is easy to use for the manufacturing process of a secondary battery, and can contribute to the efficient production of a secondary battery. Longer metal foil sheets can further improve their efficiency and contribute to the production of competitive secondary batteries at a low price.

  Moreover, according to the manufacturing method of the metal foil sheet described above, the resist ink is printed or applied in a pattern by rotary printing, and the non-etched portion can be provided seamlessly, and then the etched portion is etched. By doing so, a metal foil sheet having a continuous pattern can be manufactured very easily and at high speed. Also, by providing resist ink in a strip shape in the longitudinal direction by rotary printing, it is possible to leave that part in an unprocessed state, so it is very easy to make a metal foil sheet that is easy to use in the subsequent secondary battery manufacturing process Can be manufactured.

  When the metal foil sheet obtained by such a manufacturing method is used as a current collector for a secondary battery, any part of the metal foil sheet is provided with a continuous pattern with excellent dimensional accuracy. It is possible to efficiently perform manufacturing processes such as processing into a battery current collector, and to contribute to the efficiency of manufacturing high-performance and inexpensive secondary batteries. It can contribute to the market demand to supply to the market.

It is a front view which shows an example of the metal foil sheet of this invention. It is an enlarged view of the boundary area | region of the etching pattern and unprocessed part of the metal foil sheet | seat shown in FIG. It is BB sectional drawing of the metal foil sheet | seat 1 shown in FIG. It is process drawing which shows an example of the manufacturing method of a metal foil sheet.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, the metal foil sheet of the present invention will be described. FIG. 1 is a front view showing an example of the metal foil sheet 1 of the present invention. The metal foil sheet 1 has a continuous etching pattern 2 without a seam and an unprocessed portion 3 continuous in a strip shape in the longitudinal direction L. The metal foil sheet 1 is processed into a current collector of a predetermined size by being subjected to a process such as a cutting process which is a part of the manufacturing process of the secondary battery. The processed current collector carries an active material such as lithium salt and carbon to constitute an electrode plate, and constitutes the main material of the secondary battery together with the electrolyte material and the like. Hereinafter, the case where the metal foil sheet of the present invention is used for a current collector for a secondary battery will be mainly described. However, the present invention is not particularly limited to being used for a current collector for a secondary battery. It can also be applied to metal foil sheets for other applications where a continuous pattern is not required.

  The longer the metal foil sheet 1 is, the easier it is to handle it when it is used in the secondary battery manufacturing process, and it is possible to contribute to the efficiency of the secondary battery manufacturing process. In particular, a metal foil sheet 1 having a length of 10 m or more is preferably used. Moreover, when the metal foil sheet 1 wound up in a roll shape is processed into a current collector, the production efficiency of the processing step can be improved. The metal foil sheet 1 used for the current collector of the secondary battery is preferably copper or aluminum having a thickness of 10 μm or more and 50 μm or less. Usually, a copper foil and an aluminum foil having a thickness of about 35 μm are used. The width W of the metal foil sheet 1 is appropriately set depending on the specifications of the secondary battery and the manufacturing process of the secondary battery.

  FIG. 2 is an enlarged view of the boundary region A between the etching pattern 2 and the unprocessed portion 3 of the metal foil sheet 1 shown in FIG. The etching pattern 2 is configured by regularly providing circular through holes 4 at equal intervals, and the state is continuously provided in the longitudinal direction L of the metal foil sheet 1. In the etching pattern 2, for example, when the etching process is performed using photolithography, a seam or the like generated due to the intermittent movement of the photomask is not seen, and when the punching process is applied, No sagging, burrs, or processing distortion is seen.

  This etching pattern 2 may have a shape other than the circular through-hole 4 as shown in FIG. It may be a continuous pattern, and is not particularly limited. However, when the metal foil sheet 1 is used as a current collector for a secondary battery, the etching pattern 2 is such that charging and discharging between the electrode plate made of the current collector and the electrolyte material are performed uniformly in each part. Is preferably a pattern in which relatively small through-holes 4 having a predetermined shape are regularly arranged at regular intervals over the entire area. The shape, size, spacing, and the like of the pattern and the through-hole can be designed as appropriate.

  3 is a cross-sectional view of the metal foil sheet 1 shown in FIG. The metal foil sheet 1 of the present invention has a pattern formed by etching, and is particularly preferably formed by single-sided etching. The cross-section of the metal foil sheet 1 formed by single-sided etching is such that the opening 6 on the surface side of the through-hole 4, that is, the etching-treated surface side, is the back side of the through-hole 4, that is, the side not etched. It has a general characteristic that it is slightly larger than the opening portion 7 on the processing surface side. The single-sided etching process does not require strict position adjustment of the etching patterns on the front and back surfaces as in the case of the double-sided etching process, so that efficient production can be achieved. Moreover, since the thin metal foil sheet | seat 1 of 10 micrometers or more and 50 micrometers or less is used preferably as mentioned above, even if it is single-sided etching processing, the processing speed of the etching pattern 2 is not reduced remarkably.

  As shown in FIG. 1, the unprocessed portion 3 is continuously provided in a strip shape in the longitudinal direction L, and is usually provided with a predetermined width on both ends in the width W direction of the metal foil sheet 1. Since this unprocessed part 3 is provided in order to make it easy to use for the process which processes the metal foil sheet | seat 1 to the collector for secondary batteries of a predetermined | prescribed magnitude | size, it does not necessarily need to be the both ends side of the width direction, It may be only at one end in the width direction or at the center position. Accordingly, the unprocessed portion 3 can be provided with positioning holes, transport holes, detection marks, and the like as necessary. The width of the unprocessed portion 3, the position to be provided, and the like can be appropriately changed according to a processing apparatus or the like provided thereafter, and is not limited to the form shown in FIG. 1.

  Such a metal foil sheet 1 is appropriately processed into a size required in subsequent steps, and is used as a current collector for a secondary battery. The obtained current collector is particularly preferably used for a polymer battery using a gel electrolyte polymer containing a solvent as an electrolyte material. In the metal foil sheet 1 of the present invention, as shown in FIG. 2, the through hole 4 of the continuous pattern is seamlessly formed by etching, so that it becomes the same continuous pattern with excellent dimensional accuracy no matter what part is cut out, The solvent can be removed uniformly, and charging and discharging between the electrode plate made of the current collector and the electrolyte material can be made uniform.

  Next, the manufacturing method of the metal foil sheet 1 is demonstrated. FIG. 4 is a process diagram showing an example of a method for producing the metal foil sheet 1.

  As shown in FIG. 4, the manufacturing method of the metal foil sheet 1 includes: (a) a step of pattern printing the resist ink 13 on the metal foil sheet original 12 by rotary printing; and (b) the entire back surface of the etched surface. (C) a step of etching the etching portion 15 on one side, (d) a step of removing the etching mask 14, and (e) a step of removing the resist ink 13. Yes. The step (b) of providing the etching mask 14 on the entire back surface and the step (d) of removing the etching mask 14 are steps added in the case of single-sided etching, and are performed before and after the etching step, respectively. In this case, the step (b) may be performed before the step (a), and the pattern printing may be performed by rotary printing after the etching mask 14 is provided on the entire back surface. The etching mask 14 may be removed after the resist ink 13 has been removed.

  The step (a) of pattern printing the resist ink 13 on the metal foil sheet original 12 by rotary printing is a step for masking the non-etched portion 16 with the resist ink 13.

  The original metal foil sheet 12 is before being processed into the metal foil sheet 1 described above, and is preferably a long copper foil or aluminum foil having a thickness of 10 μm or more and 50 μm or less and rolled up in a roll shape. It is done.

  It is preferable that the resist ink 13 is easy to pattern print by rotary printing and has resistance to an etchant in the subsequent etching process. Furthermore, it is preferable that it has the property of being dissolved and removed with an alkali solvent or the like. When a general ferric chloride aqueous solution is used as an etching solution, an acid-resistant and alkali-soluble resist ink 13 such as styrene-acrylic, shellac-nitrified cotton, acrylic-cellulose, nitrified cotton-polyamide Resist inks such as those are preferably used.

  In rotary printing, a printing plate such as a gravure plate is placed on the outer periphery of a cylindrical roll, a resist ink is carried on the printing plate, and the roll is brought into contact with the surface of the original roll and rotated to obtain resist ink 13 Can be pattern-printed on the metal foil sheet original 12 in a seamless pattern. As a result, the metal foil sheet 1 described above can be manufactured extremely efficiently by subsequent etching or the like. The rotary printing is not particularly limited as long as the printing is based on the principle of pressing and rotating a cylindrical roll provided with ink on the surface of the printing material. For example, gravure printing (intaglio printing), offset printing (lithographic printing) Any printing method such as letterpress printing can be used. In particular, gravure printing is preferably used.

  The step (b) of providing the etching mask 14 on the entire back surface of the pattern-printed surface is a step provided when etching is performed by single-sided etching. Therefore, the etching mask 14 is provided with resistance to the etching solution. As such an etching mask 14, a weak adhesive film that can be laminated in a peelable manner or a coating film of an alkali-soluble resist ink is preferably used.

  The step (c) of etching the etching part 15 on one side is a step for efficiently forming an etching pattern. As the etching solution used here, one corresponding to the material of the metal foil sheet raw fabric 12 is used, but a ferric chloride aqueous solution is usually preferably used for the above-described copper or aluminum. In the present invention, since a relatively thin metal foil of 10 μm or more and 50 μm or less is preferably used, the through hole 4 can be formed without significantly reducing the etching rate even by single-sided etching. The cross section of the etched portion 15 that has been etched usually has a general characteristic that the opening 6 on the etching surface side is slightly larger than the opening 7 on the non-etching surface side (see FIG. 3). is there.

  In the step (d) of removing the etching mask 14, the etching mask 14 is peeled off by a method corresponding to the type of the etching mask 14. For example, in the case where the etching mask 14 is a weakly adhesive film, it may be simply peeled off.

  In the step (e) of removing the resist ink 13, a removing means corresponding to the type of the resist ink 13 is applied. In the case of the alkali-soluble resist ink 13, it is usually dissolved and removed with an aqueous sodium hydroxide solution. Therefore, when the above-described etching mask 14 is an alkali dissolution type, the etching mask 14 and the resist ink 13 can be dissolved and removed simultaneously.

  By such a manufacturing method, the metal foil sheet 1 having a continuous etching pattern 2 without a seam and an unprocessed portion 3 continuous in a strip shape in the longitudinal direction L can be manufactured very efficiently. Since the current collector for a secondary battery obtained by cutting or the like from the manufactured metal foil sheet 1 is provided with a continuous pattern seamlessly regardless of which part of the metal foil sheet 1 is cut. It can contribute to the efficient production of batteries, and can contribute to the supply of high-performance and inexpensive secondary batteries to the market.

  The invention is explained in more detail by means of examples.

Example 1
As the metal foil sheet original 12, a copper foil wound up into a roll having a thickness of 35 μm, a width of 500 mm, and a length of 500 m was used.

On one side of the copper foil, resist ink 13 was printed in a predetermined pattern by gravure printing. At this time, the plate for gravure printing has a plate circumference of 620 mm, a plate surface roughness of 1.5 μm (Rz), a plate surface width of 1100 mm, a plate surface hardness of 1000 Hv, and a predetermined depth controlled to a plate depth of 25 μm by photolithography. What was processed into the surface shape was used. The resist ink 13 used was an acid-resistant and alkali-soluble nitrified cotton-polyamide resist ink. The viscosity of the resist ink 13 was adjusted to 22 seconds (Zahn cup No. 3). In the gravure printing, a ceramic-coated ceraplating doctor was used and adjusted so as to maintain a doctor angle of 20 ° and a doctor pressure of 1.5 kg / cm ² . Gravure printing was performed at 40 m / min while maintaining a drying temperature of 60 ° C. As an etching pattern, resist ink is pattern-printed so that through-holes with a diameter of 1.6 mm are arranged at intervals of 2.0 mm, and the unprocessed portion has a width of 15 mm on both ends of the metal foil sheet original fabric. A resist ink was pattern printed.

Next, a polyethylene (PE) -based film having a weak adhesive adhesive made of a rubber resin was laminated as an etching mask 14 on the back surface of the surface on which the resist ink 13 was printed. The etching process was performed by single-sided etching by spraying using an aqueous ferric chloride solution as an etchant. Etching conditions at this time were an etching solution temperature of 40 ° C., a baume of 46 ° be (specific gravity), a spray pressure of 2.0 kg / cm ² , and a conveyance speed of 1.5 m / min.

Next, the weakly adhesive film was peeled off through a water washing step, and the resist ink 13 was dissolved and removed with an alkaline aqueous solution. The resist ink was dissolved and removed using a 5% aqueous sodium hydroxide solution at a temperature of 40 ° C. under a spray pressure of 1.5 kg / cm ² .

  Finally, through a water washing process, a drying process, and a winding process, a copper foil sheet having a seamless etching pattern and a non-processed continuous part in the longitudinal direction was manufactured.

(Example 2)
As the metal foil sheet raw fabric 12, an aluminum foil wound up in a roll having a thickness of 35 μm, a width of 500 mm, and a length of 500 m was used. The process of pattern printing the resist ink 13 and the process of providing the etching mask 14 were performed by the same method as in Example 1.

Prior to the etching process, a 1% sodium hydroxide aqueous solution at room temperature was pretreated by spraying the etched surface under a spray pressure of 1.0 kg / cm ² . By this pretreatment, alumite (porous oxide film) sparsely formed on the aluminum foil becomes uniform, and the subsequent etching of the aluminum foil is performed uniformly.

Etching was performed under the same conditions as in Example 1 except that the spray pressure was 4.0 kg / cm ² and the conveyance speed was 3.0 m / min.

  Next, the weakly adhesive film was peeled off through a water washing step, and the resist ink 13 was dissolved and removed with an alkaline aqueous solution. The conditions for dissolving and removing the resist ink 13 were the same as those in Example 1 except that the aqueous solution of sodium hydroxide contained a chelating agent as an inhibitor so that aluminum was not attacked by the aqueous alkaline solution (usually referred to as alkaline attack). I went there.

  Finally, an aluminum foil sheet having a continuous etching pattern without seams and an unprocessed portion continuous in a strip shape in the longitudinal direction was manufactured through a washing step, a drying step, and a winding step.

DESCRIPTION OF SYMBOLS 1 Metal foil sheet 2 Etching pattern 3 Unprocessed part 4 Through-hole 5, 16 Non-etching part 12 Metal foil sheet original fabric 13 Resist ink 14 Etching mask 15 Etching part

Claims (3)

Through holes of a predetermined shape are regularly arranged at regular intervals, and a continuous etching pattern without a seam,
An unprocessed portion that is continuous in a strip shape in the longitudinal direction,
The unprocessed portion is provided with either a positioning hole, a transport hole, or a detection mark,
A roll-shaped metal foil sheet used as a current collector for a secondary battery. Through holes of a predetermined shape are regularly arranged at regular intervals, and a continuous etching pattern without a seam,
An unprocessed portion that is continuous in a strip shape in the longitudinal direction,
The etching pattern is a pattern formed by single-sided etching,
A roll-shaped metal foil sheet used as a current collector for a secondary battery. Through holes of a predetermined shape are regularly arranged at regular intervals, and a continuous etching pattern without a seam,
An unprocessed portion that is continuous in a strip shape in the longitudinal direction,
The area of the opening portion on the front surface side of the through hole is larger than the area of the opening portion on the back surface side of the through hole,
A roll-shaped metal foil sheet used as a current collector for a secondary battery.

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