JP5082397B2 - battery - Google Patents

Description

The present invention relates to a method for manufacturing a battery including an element in which an electrode coated with an active material mixture is wound on the surface of a current collecting base material made of a strip-shaped metal foil except for a strip-shaped side edge.

  As shown in FIG. 4, the electrode used for the wound element of the non-aqueous electrolyte secondary battery is an active material on the surface excluding the left and right belt-like side edges of the current collecting base material 1 made of a belt-like metal foil. The mixture material 2 is applied, and the band-like side edge portion of the current collecting base material 1 where the active material mixture 2 is uncoated, that is, the unmixed material coated portion 1a is connected to the battery terminal via a lead or the like. Often connected. In FIG. 4 and FIG. 5 shown next, only the thicknesses of the current collecting base material 1 and the active material mixture 2 are shown on an enlarged scale for easy understanding of the drawing.

  However, when the current collector base material 1 is provided with the uncoated material portion 1a, a portion of the current collector material 1 on which the active material mixture 2 is applied in the pressing step after the application of the active material mixture 2 is performed. Only the metal foil is stretched by a press (in the case of a roll press, it is particularly stretched in the front-rear direction, which is the traveling direction of the roll press), and the metal foil of the uncoated part 1a is Since stretching does not occur, wrinkles 1b are generated in the vicinity of the boundary of the uncoated portion 1a of the current collecting base material 1, and warpage as indicated by arrows A to D is generated in the entire belt-like electrode. When such wrinkles 1b and warp occur, the electrode may not be wound correctly when the element is wound, and winding unevenness may occur.

  Therefore, conventionally, as shown in FIG. 5, the current collector is formed by forming a large number of slits 1c cut inwardly from the left and right edges in the uncoated part 1a of the current collector base material 1. The portion of the base material 1 coated with the active material mixture 2 is absorbed by the slit 1c of the uncoated material portion 1a being widened, so that wrinkles 1b and warpage are absorbed. Some have been designed to prevent the occurrence of (see, for example, Patent Documents 1 to 3).

However, when the slit 1c in the left-right direction is formed at the belt-like side edge of the current collecting base material 1, when the longitudinal tension is applied to the current collecting base material 1 in the element winding step, the slit 1c As a starting point, there is a problem that breakage in the left-right direction is likely to occur. In addition, since the metal foil of the uncoated part 1a of the composite material, which is the strip-shaped side edge of the current collecting base material 1, is divided by the slit 1c into a large number of strips, when the electrode is wound around the element, There was also a problem that the edges of adjacent strip-shaped metal foils overlapped in the vicinity of the slit 1c, resulting in an irregular outer diameter of the element. Furthermore, the strip-shaped metal foil is likely to be twisted or bent and may be broken, so that the strip-shaped metal foil of one polarity electrode comes into contact with the other polarity electrode and a soft short occurs. There is also a problem that it is difficult to connect the strip-shaped metal foil to the battery terminal via a lead or the like.
Japanese Patent Laid-Open No. 11-354103 Japanese Patent Laid-Open No. 2000-12002 JP 2000-208129 A

  In the present invention, wrinkles are generated near the boundary of the uncoated part of the composite material or the electrode is warped by forming the edge of the band-shaped side edge of the current collecting base into a wave shape by the inclined side. It is an object of the present invention to provide a battery that can prevent inconvenience such as the current collecting base material from being broken and the outer diameter of the wound element from becoming distorted.

According to a first aspect of the present invention, there is provided a battery manufacturing process comprising an element in which an active material mixture is applied to a current collecting base material made of a band-shaped metal foil. The electrode is pressed after forming the end side where the active material mixture in the base material is uncoated into a wave shape with a curved or linear inclined side inclined with respect to the longitudinal direction of the belt. To do.

  According to the first aspect of the present invention, since the end of the band-shaped side edge of the current collecting base is formed into a wave shape by the inclined side, in the pressing step after the application of the active material mixture, the current collecting base Even if only the part of the metal foil coated with the active material mixture in the material is stretched, the difference in elongation from the metal foil at the side edge of the belt-like side where the active material mixture is uncoated is the wave shape of the edge It is relieved by the concave portions of the current collector, and it is possible to prevent wrinkles or warpage of the electrodes from occurring near the boundary of the uncoated portion of the current collector base material. In addition, when the slits are formed because the end of the band-shaped side edge of the current collecting base material has a shape in which the concave and convex portions are repeated due to the wave shape of the inclined side inclined with respect to the longitudinal direction of the band As described above, it is possible to prevent inconvenience such as the outer diameter of the element in which the current collecting base material is broken or wound, and is distorted.

  In addition, the wave shape by the curved or linear inclined side inclined with respect to the belt-like longitudinal direction means that the curved or linear inclination angle exceeds −90 ° and less than + 90 ° with respect to the belt-like longitudinal direction. In the angle range (preferably the angle range where the absolute value is 22.5 ° or more and 45 ° or less), the convex and concave portions are repeated by changing continuously or stepwise alternately between positive and negative across 0 °. Refers to the shape. As a wave shape by the curved inclined side, for example, there is a sine wave shape, and the inclination angle of the inclined side changes continuously and alternately to positive and negative angles while passing through 0 °, thereby forming convex portions and concave portions. Will be repeated. Further, as a wave shape by a linear inclined side, for example, there is a triangular wave shape of an isosceles triangle, and the inclination angle of the inclined side alternately changes to two angles having an equal positive and negative absolute value exceeding 0 °. Thus, the convex part and the concave part are repeated.

  However, the triangular wave shape of a right triangle or the rectangular wave shape of a pulse shape does not have a wave shape due to the above-mentioned inclined side because there are end sides orthogonal to the longitudinal direction of the belt at an angle of ± 90 °. When there is an end perpendicular to the longitudinal direction as described above, the current collecting base material may be broken or bent starting from the end of the recess on the concave side as in the case where the slit is formed. Because.

  Hereinafter, the best embodiment of the present invention will be described with reference to FIGS. Also in these drawings, the same reference numerals are given to constituent members having the same functions as those of the conventional example shown in FIGS. Moreover, in FIG.2 and FIG.3, in order to make drawing easy to understand, only the thickness of the current collection base material 1 and the active material compound material 2 is expanded and shown.

  In the present embodiment, a non-aqueous electrolyte secondary battery including a long cylindrical winding element 3 as shown in FIG. 1 will be described. The element 3 is obtained by winding a belt-like positive electrode 4 and a negative electrode 5 in a long cylindrical shape with a separator 6 interposed therebetween.

  As shown in FIG. 2, the positive electrode 4 and the negative electrode 5 (electrodes 4 and 5) are obtained by coating the active material mixture 2 on the surface of the current collecting base material 1. The current collecting base material 1 is a strip-like metal foil that is long in the front and rear direction. In the case of the positive electrode 4, an aluminum foil is used, and in the case of the negative electrode 5, a copper foil is used. In the case of the positive electrode 4, the active material mixture 2 is a mixture of a positive electrode active material such as lithium cobalt composite oxide and a binder, and in the case of the negative electrode 5, a mixture of a negative electrode material such as graphite and a binder. is there.

  A manufacturing process of the electrodes 4 and 5 will be described. The active material mixture 2 is coated on the surface of the current collecting base material 1 that is long in the front and rear directions over the front and rear portions of the left and right belt-like side edges, that is, most of the left and right centers. Therefore, the left and right belt-like side edge portions of the current collecting base material 1 become composite material uncoated portions 1a and 1a where the active material composite material 2 is uncoated.

  The current collecting base material 1 has left and right belt-side edge portions 1d and 1d formed in a wave shape. That is, each end side 1d is formed in a repetitive shape of a convex portion projecting to the left and right outer sides and a concave portion drawn into the left and right inner sides. In addition, the recessed part of this edge 1d should just be drawn inward in the range which does not reach the coating part of the active material compound material 2, ie, the width of the left-right width of the compound material uncoated part 1a, and is most drawn in. It is preferable that there is a sufficient distance until the portion reaches the coating portion of the active material mixture 2. Accordingly, the left and right maximum wave widths of the convex and concave portions are narrower than the left and right maximum widths of the unmixed material uncoated portion 1a, and 1/3 of the maximum left and right widths of the unmixed material uncoated portion 1a. It is preferably about 1/5.

  The wave shape of the edge 1d is a sine wave shape in which the inclination angle of the curve regularly changes smoothly and continuously in FIG. 2, but is not necessarily limited to this shape. For example, FIG. As shown in FIG. 4, it may be a triangular wave shape of an isosceles triangle in which straight lines having different inclination angles are continuously connected. Further, it is not always necessary to repeat regularly. For example, as shown in FIG. 1, a convex portion is formed by a portion disposed on the inner peripheral side and a portion disposed on the outer peripheral side when wound around the element 3. The repetitive pitch between the part and the concave part may be different, or the shape of the convex part or the concave part which is irregular to some extent may be repeated.

  However, the edge 1d is formed in a wave shape with a curved or linear inclined side inclined with respect to the longitudinal direction of the belt, so that the curved or linear inclination angle is relative to the longitudinal direction of the belt. They must intersect at an angle without intersecting at right angles, that is, intersect in an angle range of more than −90 ° and less than + 90 ° (preferably an angle range in which the absolute value is 22.5 ° or more and 45 ° or less) ( As will be described below, the tilt angle changes, so it is not fixed at 0 °). And since it is a wave shape, this curve-form or linear inclination angle will repeat a convex part and a recessed part by changing positive or negative alternately continuously or in steps over 0 degree. As the wave shape by the curved inclined side, for example, there is a sine wave shape as shown in FIG. 2, and the inclination angle of this inclined side is an angle range from about −40 ° to about + 40 ° while passing through 0 °. By alternately and continuously changing, the convex part and the concave part are repeated. Further, as a wave shape by the linear inclined side, for example, there is a triangular wave shape of an isosceles triangle as shown in FIG. 3, and the inclination angle of this inclined side exceeds 0 ° and is about −28 ° and about + 28 °. By alternately changing to these two angles, the convex portion and the concave portion are repeated.

  When the active material mixture 2 is coated on the surface of the current collecting base material 1, the active material mixture 2 is conveyed forward or rearward in the longitudinal direction and pressed by passing through a roll press (not shown). However, in this pressing step, only the coated portion of the active material mixture 2 that has been coated and raised on the surface of the current collecting base material 1 is pressed. The engineering parts 1a and 1a are not pressed. For this reason, the metal foil of the current collecting base material 1 is stretched in the front-rear direction, which is the traveling direction of the roll press, in the coated portion of the active material mixture 2 as in the prior art. The material uncoated portions 1a and 1a are not stretched.

  However, the uncoated portions 1a and 1a of the current collecting base material 1 of the present embodiment have a wave shape in which the end sides 1d and 1d are a repetition of a convex portion and a concave portion. Becomes narrower than the convex portion, and the metal foil in the concave portion is easily stretched back and forth. Therefore, even if only the metal foil of the coated portion of the active material mixture 2 in the current collector base material 1 is stretched back and forth by the pressing process, the uncoated portions 1a and 1a on the left and right sides are also In addition, it is possible to prevent wrinkles and warpage from being generated by stretching the metal foils of the concave portions that are repeatedly formed. In addition, since these composite material uncoated portions 1a and 1a have sufficiently wide left and right widths of the convex portions, these portions can be easily connected to battery terminals via leads or the like.

  The current collecting base material 1 that has completed the pressing step is divided into two at the left and right centers together with the active material mixture 2 to become electrodes 4 and 5. Therefore, as shown in FIG. 1, in the electrodes 4 and 5 of the present embodiment, only one band-like side edge portion becomes the mixture uncoated portion 1 a, and only the edge 1 d of the mixture uncoated portion 1 a is formed. It is formed into a wave shape by repetition of convex portions and concave portions. In FIG. 1, the positive electrode 4 is slightly shifted upward with the uncoated material portion 1 a facing upward, and the negative electrode 5 is wound while being slightly shifted downward with the uncoated material portion 1 a facing downward. Thus, the uncoated portion 1a of the positive electrode 4 protrudes from the upper end surface of the element 3, and the uncoated portion 1a of the negative electrode 5 protrudes from the lower end surface of the element 3. .

  The element 3 wound as described above is housed in a battery container (not shown) and filled with a non-aqueous electrolyte to form a non-aqueous electrolyte secondary battery. In addition, each uncoated portion 1a of the composite material 4a of the electrodes 4 and 5 protruding from the upper and lower end faces of the element 3 is connected to a terminal of the nonaqueous electrolyte secondary battery via a lead or the like.

  According to the said structure, it can prevent that a wrinkle generate | occur | produces in the current collection base material 1, or a curvature arises in the electrodes 4 and 5. Moreover, since only the wave shape by the inclined side is formed on the end side 1d of the mixed material uncoated portion 1a of the current collecting base material 1, the electrodes 4 and 5 are wound in the front-rear direction for winding the element 3. Even if tension is applied, there is no possibility that the current collecting base material 1 is broken as in the case where a slit is formed in which the end 1d is perpendicular to the longitudinal direction of the belt. In addition, even if the electrodes 4 and 5 are wound, the metal foil of the uncoated portion 1a of the current collecting base material 1 does not overlap or twist or bend, so the outer diameter of the element 3 is distorted. The occurrence of soft shorts can be prevented. Furthermore, the uncoated material-coated portion 1a of the electrodes 4 and 5 has a sufficiently wide wave-shaped convex portion, so that it can be easily connected to a battery terminal via a lead or the like.

  In the above embodiment, only the band-like side edge on either the left or right side of the current collecting base material 1 of the electrodes 4 and 5 is used as the uncoated material part 1a, and its end 1d is a wave in which convex parts and concave parts repeat. Although the case where it formed in the shape was shown, the band-like side edge part of right and left both sides was made into unmixed material coated part 1a, 1a, and these edge sides 1d and 1d were formed in the wave shape which a convex part and a crevice repeat, respectively. Also good. That is, the current collecting base material 1 shown in FIGS. 2 and 3 may be used as the electrodes 4 and 5 without being divided into left and right parts.

  In the above embodiment, the active material mixture 2 is applied only to one surface (the upper surface in FIGS. 2 and 3) of the current collecting substrate 1, but the active material mixture 2 is applied to both surfaces of the current collecting substrate 1. The material mixture 2 may be applied. Furthermore, in the said embodiment, although the case where the edge 1d of the mixed material uncoated portion 1a of the current collecting base material 1 of both the positive electrode 4 and the negative electrode 5 was formed in a wave shape in which the convex portion and the concave portion were repeated, Only one of the positive electrode 4 and the negative electrode 5 may be used. That is, when wrinkles or warpage is likely to occur only in one of the positive electrode 4 and the negative electrode 5, only the edge 1d of the uncoated portion 1a of the current collector base material 1 of the positive electrode 4 or the negative electrode 5 is used. You may make it the waveform which a convex part and a recessed part repeat.

  Moreover, although the said embodiment demonstrated the nonaqueous electrolyte secondary battery provided with the long cylindrical winding type element 3, if it is a battery provided with the winding type element, the winding shape of an element and a battery These types are arbitrary, and are not limited to those shown in the embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view illustrating an embodiment of the present invention and showing elements being wound. FIG. 3 is a partially enlarged perspective view showing a part of a band-like electrode before winding around an element, the end of which has a sine wave shape, showing an embodiment of the present invention. 1 is a partially enlarged perspective view showing a part of a strip-like electrode before winding around an element and having a wave shape at an end of an isosceles triangular shape, showing an embodiment of the present invention. It is. It is a partial expansion perspective view which shows a prior art example and shows a part of strip | belt-shaped electrode before winding around an element. It is a partial expansion perspective view which shows a prior art example, Comprising: It is a strip | belt-shaped electrode before winding around an element, Comprising: It is a partially expanded perspective view which shows what formed the slit in the uncoated material coating part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Current collection base material 1a Mixture uncoated part 1b 皺 1c Slit 1d Edge 2 Active material mixture 3 Element 4 Positive electrode 5 Negative electrode 6 Separator

Claims (1)

In a method for manufacturing a battery comprising an element in which an active material mixture is applied to a current collecting base material made of a strip-shaped metal foil, an active material mixture in the current collecting base material of at least one of positive and negative electrodes A method for producing a battery , comprising: forming an uncoated end side into a wave shape with a curved or linear inclined side inclined with respect to the longitudinal direction of the belt, and then pressing the electrode .

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