JP6036627B2 - Method for manufacturing power storage device - Google Patents

Description

  The present invention relates to a method for manufacturing a power storage device.

  Conventionally, as a secondary battery which is a kind of power storage device, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery is well known. In such a secondary battery, an electrode assembly is formed by laminating or winding an electrode (positive electrode or negative electrode) having an active material layer on the surface and a separator as a power storage element, and the electrode assembly is mounted on a case. It has a housed configuration.

  For example, Patent Documents 1 and 2 below disclose a technique for manufacturing a secondary battery by applying an active material layer to the surface of a strip-shaped metal foil sheet and then punching it into the shape of each electrode.

JP 2011-134479 A JP 2009-266739

  In recent years, a technique for covering an active material layer coated on a metal foil sheet with a ceramic layer has been developed for the purpose of improving insulation between electrodes.

  However, when the active material layer is covered with the ceramic layer, the position detection camera cannot detect the position of the active material layer. This is more effective than the coated part of the active material layer so that no part of the active material layer that is not covered with the ceramic layer is generated on the active material layer even if there is misalignment due to manufacturing errors. By setting the area of the covering portion of the layer large. For this reason, the outer periphery of the active material layer is covered with the ceramic layer. For this reason, it is difficult to punch the metal foil with high positional accuracy, and when the punching position is greatly shifted, the electrode characteristics are deteriorated.

  Accordingly, an object of the present invention is to provide a method for manufacturing a power storage device in which electrode characteristics are improved.

  A method for manufacturing a power storage device according to one embodiment of the present invention is a method for manufacturing a power storage device including an electrode having an active material layer on a surface, and is provided on a surface of a strip-shaped metal foil sheet to be a transported electrode. A coating process for coating the material layer, a coating process for forming a ceramic layer entirely covering the active material layer on the surface of the metal foil sheet, an active material layer is applied, and a ceramic layer is formed. An active material layer on the surface of the metal foil sheet after the coating process and before the coating process. It further includes a marking process for forming a mark based on the position.

  In this power storage device manufacturing method, the mark formed on the surface of the metal foil sheet in the marking process can be used for position detection in the subsequent punching process. Therefore, it can be punched into the shape of the electrode with high positional accuracy, and high electrode characteristics can be realized.

  Moreover, the aspect which further includes the press process which presses an active material layer after a coating process and before a coating | coated process, and performs a marking process after a press process may be sufficient. Even when the dimension and shape of the active material layer change in the pressing process, the marking process can be performed after the pressing process, so that the metal foil can be punched with high positional accuracy.

  Further, in the coating process, the strip-shaped active material layer may be continuously applied along the conveying direction of the metal foil sheet, or may be intermittently rectangular along the conveying direction of the metal foil sheet. The form which coats the active material layer of a shape may be sufficient.

  Note that the power storage device may be a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrical storage apparatus by which the improvement of the electrode characteristic was aimed at is provided.

FIG. 1 is a flowchart illustrating a method for manufacturing a power storage device according to an embodiment of the present invention. FIG. 2 is a diagram showing one step of the manufacturing method shown in FIG. FIG. 3 is a diagram showing a step of the manufacturing method shown in FIG. 4A is a view showing one step of the manufacturing method shown in FIG. 1, and FIG. 4B is a cross-sectional view taken along line IVb-IVb. FIG. 5 is a diagram showing dimensions and shapes of the electrodes. FIG. 6 is a diagram showing one step of a manufacturing method of a different mode. FIG. 7 is a diagram showing one step of a manufacturing method of a different mode. FIG. 8: is the figure which showed 1 process of the manufacturing method of a different aspect, (b) It is a VIIIb-VIIIb sectional view taken on the line.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  FIG. 1 is a flowchart illustrating a method for manufacturing a secondary battery as a method for manufacturing a power storage device. As shown in FIG. 1, this manufacturing method includes a coating step S10, a drying step S12, a pressing step S14, a covering step S16, and a punching step S18.

  In coating process S10, as shown in FIG. 2, the strip | belt-shaped metal foil sheet 10 wound by roll shape is unwound one by one, and the active material layer 12 is coated on the surface.

  The metal foil sheet 10 is a sheet to be an individual metal foil constituting the electrode of the power storage device. For example, the metal foil sheet 10 is made of copper for the negative electrode and aluminum for the positive electrode. The metal foil sheet 10 is conveyed in the conveyance direction D in a state where the surface is sufficiently stretched.

  The active material layer 12 is a layer containing an active material such as a metal oxide or a carbon material, a conductive material, a binder, and a thickener, and a slurry containing a solvent when applied in the coating step S10. State. The active material layer 12 is continuously coated on the surface of the metal foil sheet 10 with a uniform width and a uniform thickness along the conveyance direction D of the metal foil sheet 10.

  In the drying step S12, the active material layer 12 coated on the surface of the metal foil sheet 10 in the coating step S10 is dried under predetermined drying conditions. By the drying, in the active material layer 12, the solvent and the like contained therein are evaporated.

  In the pressing step S14, the active material layer 12 dried in the drying step S12 is pressed by a roll press. The active material layer 12 is solidified with high density by pressing. Note that the dimensions and shape of the active material layer 12 slightly change before and after pressing (for example, about 1 mm at the maximum) due to the pressure during pressing, for example, the active material layer 12 extends in the width direction.

  In the covering step S16, the active material layer 12 pressed in the pressing step S14 is entirely covered with the ceramic layer 14. Similarly to the active material layer 12 described above, the ceramic layer 14 is applied to the surface of the metal foil sheet 10 along the conveyance direction D of the metal foil sheet 10 with a uniform width and a uniform thickness. The width of the ceramic layer 14 is wider than the width of the active material layer 12, and the ceramic layer 14 covers both ends of the active material layer 12 in the width direction. As a material of the ceramic layer 14, for example, alumina, silica, titanium oxide, and a mixture thereof can be employed.

  The active material layer 12 and the ceramic layer 14 described above are provided not only on the surface of the metal foil sheet 10 but also in the corresponding region on the back surface of the metal foil sheet 10 as shown in FIG.

  In the punching step S18, the region where the active material layer 12 is applied and the ceramic layer 14 is formed in the metal foil sheet 10 is punched into the shape of the electrode 20 shown in FIG. As shown in FIG. 5, the electrode 20 has a shape in which a rectangular tab portion 24 protrudes from one side of the rectangular main body portion 22. The active material layer 12 described above is formed on the entire surface of the main body 22. On the other hand, in the tab portion 24, the active material layer 12 is formed only in a partial region close to the main body portion 22, and the active material layer 12 is not formed in other regions. The electrode 20 is electrically connected to the electrode terminal of the secondary battery in the region of the tab portion 24 where the active material layer 12 and the ceramic layer 14 are not formed. For the punching, a known punching machine (cutting device) can be used. The punching is performed in two stages: punching in the direction along the conveyance direction D of the metal foil sheet 10 and punching in the direction along the width direction of the metal foil sheet 10. It is carried out. In addition, the electrode 20 is laminated | stacked in the subsequent process, and comprises the electrode assembly of a secondary battery.

  Here, when the electrode 20 is used for a negative electrode, for example, the width W is 136 mm and the height H is 108.5 mm. Moreover, the height of the area | region in which the active material layer 12 of the tab part 24 was formed is 4 mm. Since the dimensions of the electrode 20 greatly affect the electrode characteristics, high accuracy is required. The requirement for the dimensional accuracy is, for example, within an error of ± 0.5 mm.

  However, when the active material layer 12 formed on the surface of the metal foil sheet 10 is covered with the ceramic layer 14 as in the manufacturing method described above, the position of the active material layer 12 (for example, the active material layer) is detected by a position detection camera. 12 edge positions) cannot be detected. Therefore, in the punching step S18, the position of the region of the electrode 20 to be punched cannot be obtained with high accuracy.

  Therefore, in the present embodiment, a marking step S20 is included between the coating step S10 and the covering step S16 described above, and more specifically, between the pressing step S14 and the covering step S16.

  In the marking step S <b> 20, a mark M is formed on the surface of the metal foil sheet 10 with the application position of the active material layer 12 as a reference. The mark M is linear, and extends in parallel with one side forming the outer peripheral edge with the active material layer 12 (that is, extends along the transport direction D) as shown in FIG. The layer 12 is formed so as to be separated from one side of the outer peripheral edge by a predetermined distance (for example, 2 to 3 mm). For the formation of the mark M, a pen, an inkjet, a dispenser, a roller marker, a tape, or the like can be used. The shape of the mark M is not limited to a straight line shape, and may be a short straight line shape orthogonal to the mark M, a cross shape, a triangular or square dot shape, or a combination thereof.

  As shown in FIG. 4, the mark M is provided at a position that is not covered by the ceramic layer 14 in the covering step S16 and is exposed from the ceramic layer 14 even after the covering step S16. Can be detected. That is, the mark M can be used for position detection in the punching step S18 performed after the covering step S16.

  Therefore, in the above-described method for manufacturing a power storage device, the metal foil sheet 10 can be punched into the shape of the electrode 20 with high positional accuracy, and high electrode characteristics can be realized.

  In the above-described method for manufacturing the power storage device, the marking step S20 is performed after the pressing step S14. Therefore, when the dimensional shape of the active material layer 12 is changed in the drying step S12 or the pressing step S14, the mark M can be formed in the marking step with reference to the position of the active material layer 12 in which the dimensional shape has changed. Therefore, the electrode 20 can be punched into the shape of the electrode 20 with higher positional accuracy than in the case where the position of the active material layer 12 before the dimensional shape is changed is used as a reference.

  In the above description, the continuous coating in which the active material layer 12 is continuously applied to the surface of the metal foil sheet 10 has been described, but also in the intermittent coating in which the active material layer is intermittently applied. Have the same effect.

  In intermittent coating, in the coating step S10, a rectangular active material layer 12A is formed on the surface of the metal foil sheet 10 as shown in FIG. The active material layers 12 </ b> A are formed in the same shape at predetermined intervals along the conveyance direction D of the metal foil sheet 10. Further, in the marking step S20, as shown in FIG. 7, in the width direction of the metal foil sheet 10, the region between the adjacent active material layers 12A is separated from the corresponding active material layer 12A by a predetermined distance. An extending mark M is formed. Further, in the covering step S16, as shown in FIG. 8, each active material layer 12A is entirely covered with a rectangular ceramic layer 14A. The mark M is provided at a position that is not covered by the ceramic layer 14A in the coating step S16, and is exposed from the ceramic layer 14A even after the coating step S16.

  Therefore, not only continuous coating but also intermittent coating, the mark M exposed from the ceramic layer 14A can be used for position detection in the punching step S18 performed after the coating step S16. Thereby, the metal foil sheet 10 can be punched into the shape of the electrode 20 with high positional accuracy, and high electrode characteristics can be realized.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

  For example, the power storage device is not limited to a secondary battery such as a lithium ion secondary battery, but may be another power storage device (for example, an electric double layer capacitor or a lithium ion capacitor).

  DESCRIPTION OF SYMBOLS 10 ... Metal foil sheet | seat, 12, 12A ... Active material layer, 14, 14A ... Ceramic layer, 20 ... Electrode, M ... Mark.

Claims (5)

A method of manufacturing a power storage device including an electrode having an active material layer on a surface,
A coating step of coating the active material layer on the surface of the strip-shaped metal foil sheet to be transported, and
A coating step of forming a ceramic layer that entirely covers the active material layer on the surface of the metal foil sheet;
A stamping step in which the active material layer is applied and the metal foil sheet in the region where the ceramic layer is formed is punched into the shape of the electrode;
The electric storage further includes a marking step for forming a mark based on the coating position of the active material layer on the surface of the metal foil sheet after the coating step and before the covering step. Device manufacturing method. A pressing step of pressing the active material layer after the coating step and before the coating step;
The method for manufacturing a power storage device according to claim 1, wherein the marking step is performed after the pressing step.   The manufacturing method of the electrical storage apparatus of Claim 1 or 2 which coats the said strip | belt-shaped active material layer continuously along the conveyance direction of the said metal foil sheet in the said coating process.   The manufacturing method of the electrical storage apparatus of Claim 1 or 2 which coats the rectangular-shaped active material layer intermittently along the conveyance direction of the said metal foil sheet in the said coating process.   The manufacturing method of the electrical storage apparatus as described in any one of Claims 1-4 whose said electrical storage apparatus is a secondary battery.

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