JP4632860B2 - Secondary battery and manufacturing method thereof - Google Patents

Description

  The present invention relates to a secondary battery using an electrode sheet and a separator and a method for manufacturing the same, and more particularly to a secondary battery that can be manufactured stably and at high speed by a simple method and a method for manufacturing the same.

  In electronic devices such as portable telephones, lithium ion secondary batteries that can improve the performance and capacity of the main power source are known as promising batteries. In general, this type of sealed secondary battery is formed by interposing a separator between a sheet-like positive electrode and a negative electrode, and winding or stacking to form an electrode group. It is made by sealing inside.

  Both sheet-shaped electrodes are coated with an electrode active material on a 10-20 μm sheet-shaped current collector made of aluminum or copper, subjected to a rolling process to improve density, and cut or punched to the required dimensions and shape. And then separated. In addition, in application | coating of an electrode active material, the non-coating area | region of the electrode active material for welding lead foil required when forming an electrode group is provided. This non-coating region is sufficient to be equal to or smaller than the width dimension of the electrode, and unnecessary portions may be excluded.

  The separator is made of a polyethylene or polypropylene film with fine pores of about 20-30 μm. When the separator is sandwiched between the positive electrode sheet and the negative electrode sheet and the inside of the battery is overheated, the holes provided in the separator are melted. Then the hole is closed.

  FIG. 3 shows an electrode laminate for a lithium ion secondary battery according to the above-described prior art, FIG. 3 (a) is a plan view thereof, and FIG. 3 (b) is a schematic sectional view thereof.

  As shown in FIG. 3A, the lead portion formed in the non-coated region 3 is drawn out from the electrode laminated portion 38. 3B, the electrode active material 2 is applied to the front and back surfaces of the current collector 1 except for the non-coated region 3 corresponding to the leads, and compressed. After the electrode sheet is cut into a battery shape, negative electrode sheets and positive electrode sheets are alternately stacked, and a separator 5 cut into a battery shape is inserted between the positive electrode and the negative electrode. In addition, in FIG.3 (b), the electrode sheet 6 cut | disconnected of the same pole was displayed by equal height.

  At the time of this lamination, the separator 5 is made of polyethylene or polypropylene having a thickness of 20 to 30 μm and is very thin, so it has no rigidity and is difficult to handle.

  With respect to the above problem, Patent Document 1 and Patent Document 2 disclose a method in which a separator is integrated with an electrode sheet by a coating method, a laminating method, a transfer method, or heat welding to facilitate handling. However, forming a porous separator by a coating method, a laminating method or a transfer method (Patent Document 1), or pasting it on an electrode surface by thermal welding (Patent Document 2) means that the porous characteristics of the separator In practice, this is a difficult method.

Japanese Patent Laid-Open No. 10-50348 JP 2000-285955 A

  In the above-described conventional example, when laminating the positive electrode, the negative electrode, and the separator, a 20-30 μm polyethylene or polypropylene non-rigid separator sheet is handled alone, which makes handling very difficult.

  The present invention has been made to solve such problems, and the technical problem thereof is a secondary battery having a laminated structure of a separator and an electrode that can be easily laminated in a secondary battery using a thin separator, and the same. It is to provide a manufacturing method.

  In the present invention, in order to solve the above-described problems, when the separator and the electrode are stacked, a part of the separator is welded to the electrode to facilitate the handling of the separator. As a means for this, in the electrode cutting apparatus, after the separator is overlapped on the front and back of the belt-like electrode, the separator and the belt-like electrode are cut by a cutting mechanism with a heater, and the separator is welded to the electrode end.

That is, the secondary battery of the present invention is a secondary battery in which positive and negative electrodes obtained by applying an electrode active material to a thin plate current collector are stacked via a porous separator, and the electrode active material is A porous separator is applied to both sides of the current collector, and a porous separator is overlaid so as to cover the electrode active material. The electrode and the porous separator have a cut end, and the cut end of the porous separator. Is welded to the cut end of one of the positive and negative electrodes, and the porous separator and the electrode are integrated .

  Further, the method for producing a secondary battery of the present invention is a method for producing a secondary battery in which positive and negative electrode sheets formed by applying an electrode active material on both sides of a current collector are laminated via a porous separator, A step of exposing the band-like part at one side end of the band-shaped current collector and continuously applying an electrode active material to the remaining part to produce a band-shaped electrode sheet; and the both sides of either the positive or negative band-shaped electrode sheet The step of producing a belt-like laminated arrangement sheet by overlaying a porous separator so as to cover the electrode active material, and the cutting portion of the porous separator is formed by the cutting mechanism using a punching blade with a heater. And a step of cutting so as to be welded to the cutting portion of the sheet.

  By adhering the separator to the electrode sheet and integrating it with the electrode sheet, it becomes unnecessary to handle a non-rigid separator alone, so a stable secondary battery structure is constructed, and an inexpensive secondary battery and The manufacturing method can be provided.

  First, the outline of the secondary battery manufacturing process in the embodiment of the present invention will be described. The electrode active material is continuously applied to the sheet-shaped current collector except for the non-coating region for welding the lead foil, and then rolled to form a reel. For either positive or negative electrode sheet, pull the electrode sheet from the electrode reel, place the separator on top and bottom so as to cover the electrode active material, and place the separator end on the electrode by a cutting mechanism using a punching blade with a heater. And is cut and separated to a predetermined size. The secondary battery of the present embodiment is obtained by stacking it together with the other electrode sheet cut.

  Next, a description will be given based on the drawings. FIG. 1 shows a method for manufacturing a lithium ion secondary battery according to an embodiment of the present invention, FIG. 1 (a) is a plan view showing a method for laminating and cutting electrodes and separators, and FIG. It is the front view. First, the electrode active material 2 is continuously applied to the front and back surfaces of the current collector 1 except for the strip-shaped non-coating region 3 corresponding to the lead, and then pressed and compressed to a predetermined electrode thickness to form an electrode reel 41. . Next, as shown in FIG. 1, the separator 5 drawn out from the roll-shaped separator 51 is disposed so as to cover the electrode active material 2 on the front and back of the electrode sheet drawn out from the electrode reel 41. Next, the electrode sheet is cut into a battery shape together with the separator 5 by the cutting mechanism 8 equipped with the cutting blade 7 with a heater. At that time, the separator 5 comes into contact with the cutting blade 7 with a heater, and the contact portion is thermally melted. The heater-equipped cutting blade 7 is separated immediately, and the heat-dissolving part of the separator 5 adheres to the battery-shaped electrode sheet 6 and is integrated. At this time, the temperature of the cutting blade 7 with a heater is set to about 190 ° C.

  FIG. 2 is a diagram showing the structure of a lithium ion secondary battery laminate produced by the above method. FIG. 2A is a plan view of the whole, and 28 indicates a laminated portion of the electrodes. FIG. 2B is a cross-sectional view showing the laminated state. The end of the separator 5 is melted by heat at the time of cutting, and is adhered to the cut end of the electrode sheet 6.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and design changes within a range not departing from the gist of the present invention are also included in the present invention. That is, it goes without saying that various modifications and corrections that can be made by those skilled in the art are included.

FIGS. 1A and 1B are a plan view and a front view, respectively, illustrating a method for manufacturing a lithium ion secondary battery according to an embodiment of the present invention, in which FIG. The structure of the lithium ion secondary battery laminated body which concerns on one embodiment of this invention is shown, Fig.2 (a) is a whole top view, FIG.2 (b) is sectional drawing which shows the lamination | stacking state. The electrode laminated body for lithium ion secondary batteries of a prior art example is shown, Fig.3 (a) is the top view, FIG.3 (b) is the typical sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current collector 2 Electrode active material 3 Non-coating area | region 5 Separator 6 Electrode sheet 7 Cutting blade 8 with a heater Cutting mechanism 28,38 Laminating part 41 Electrode reel 51 Roll-shaped separator

Claims (2)

A secondary battery in which a positive and negative electrode formed by applying an electrode active material to a thin plate current collector is laminated via a porous separator, the electrode active material being applied to both surfaces of the current collector, A porous separator is overlaid so as to cover the electrode active material, the electrode and the porous separator have a cut end, and the cut end of the porous separator is one of the positive and negative electrodes of the electrode. A secondary battery welded to a cut end portion of an electrode , wherein the porous separator and the electrode are integrated .   A method of manufacturing a secondary battery in which a positive and negative electrode sheet formed by applying an electrode active material on both sides of a current collector is laminated via a porous separator, wherein the belt-shaped current collector has a belt-like shape at one side end. A step of exposing a part and continuously applying an electrode active material to the remaining part to produce a strip electrode sheet, and a porous separator so as to cover the electrode active material on both sides of either the positive or negative strip electrode sheet A step of producing a belt-like laminated arrangement sheet, and a step of cutting the laminated arrangement sheet so that the cut portion of the porous separator is welded to the cut portion of the electrode sheet by a cutting mechanism using a punching blade with a heater. The manufacturing method of the secondary battery characterized by including.

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