JP2005339930A - Wound battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wound battery having high performance and long life by equalizing pressure applied to an electrode winding body of the wound battery in which the electrode winding body is sealed in a square hard case, and to provide the manufacturing method of the wound battery. <P>SOLUTION: The wound battery 1 has an electrode body 20 formed by winding an electrode sheet and a separator sheet and the square hard case (a case 10 and a cover 11) for housing the electrode body 20, the electrode body 20 has two folding back parts R and a flat part P between the folding back parts, both peak parts of two folding back parts R and both outer surfaces of the flat part P of the electrode body 20 adhere closely to the inner surface of the square hard case, winding of the electrode sheet and the separator sheet is stopped in a part other than the peak parts out of the outer circumference of the folding back parts R. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wound battery having an electrode winding body formed by winding a positive and negative electrode plate and a separator sheet, and a method for manufacturing the same. More specifically, the present invention relates to a wound battery in which an electrode winding body is housed in a rectangular hard case and a method for manufacturing the same.

  Conventionally, a battery having an electrode body in which a positive electrode plate and a negative electrode plate are wound around a separator sheet is used. When manufacturing such a wound electrode body, the ends of the positive electrode plate, the negative electrode plate, and the separator sheet are fixed to the winding core of the winding machine, and the winding core is rotated while applying a predetermined tension. Then, when the sheet is wound to a predetermined length, each sheet is cut. Furthermore, the end is fixed with tape or the like to prevent rewinding or loosening.

  In addition, many batteries in which such a wound electrode body is enclosed in a can case or the like having a very high rigidity compared to the electrode body have been manufactured. In this case, since the electrode body repeatedly expands and contracts in the case due to the charging and discharging of the battery, the pressure contact state between the case and the electrode body changes. On the other hand, a battery in which a pressure plate is provided between the case and the electrode body so that the pressure is not concentrated has been devised (for example, see Patent Document 1).

There is also a flat battery such as a button battery in which a wound electrode body is enclosed in a flat metal case, and the flat surface of the metal case also serves as an electrode. In such a battery, a battery in which the end of the electrode body is fixed with an insulating tape or an adhesive at the curved portion on the side surface of the electrode body to prevent winding deviation and loosening and to obtain good battery characteristics has been devised. (For example, refer to Patent Document 2).
JP 2000-357535 A (FIG. 2) JP 2002-289257 A (FIG. 1)

  However, the battery described in each of the above-mentioned documents is a device that has some space between the electrode body and the case. In the battery of Patent Document 1, a pressure plate is inserted and a gap is provided between the case and the electrode body. In the battery of Patent Document 2, the flat portion of the electrode body is almost in close contact with the metal case, but the side surface portion has some margin. However, in recent years, the length of the electrode body enclosed inside has increased with the increase in capacity of the battery, while the case itself is not so large from the viewpoint of space saving. For this reason, there is an electrode body and a case with almost no allowance on either the flat surface portion or the side surface portion. In the battery thus formed, these ideas could not be used as they were.

  This is because in such a battery, when the electrode body expands due to charging / discharging, both the flat surface portion and the side surface portion of the electrode body are in pressure contact with the can case. In that state, a large pressure is applied to the electrode body at a portion where the pressure plate or the insulating tape is in contact with the electrode body. In particular, pressure may be concentrated at the stepped portion due to these end portions. As a result, the electrode body may be deformed at that portion, and the active material may be peeled off or dendrites may be generated. In such a case, there is a problem that a failure due to a voltage drop occurs or the life is shortened.

  The present invention has been made in order to solve the problems of the conventional wound battery and the method of manufacturing the same. That is, the problem is that the electrode winding body of the winding type battery in which the electrode winding body is enclosed in a rectangular hard case has a uniform pressure applied to the electrode winding body, has high battery performance, and has a long life. It is in providing the winding type battery which can be obtained, and its manufacturing method.

  The wound battery of the present invention made for the purpose of solving this problem is a wound type battery having an electrode winding body formed by winding an electrode sheet and a separator sheet, and a rectangular hard case that houses the electrode winding body. In the battery, the electrode winding body is a winding method having two folded portions and a flat portion between them, and the top and the flat portions of the two folded portions of the electrode winding body. Both the outer surfaces are closely attached to the inner surface of the square hard case, and the electrode sheet and the separator sheet are wound around the outer periphery of the folded portion other than the top of the head.

  In the wound battery of the present invention, the electrode winding body is a flat type in which an electrode sheet and a separator sheet are wound so as to have two folded portions and a flat portion therebetween. In particular, when this electrode winding body is housed in a rectangular hard case, there is an electrode winding body in such an amount that both the tops of the two folded portions and the outer surfaces of the flat portions are in close contact with the inner surface of the rectangular hard case. It is what you are doing. The folded portion of each sheet is generally curved so as not to crease the sheet, and the square hard case has a corner, so that there is a gap between them other than the top of the head. Here, in the present invention, each sheet is fastened at a place other than the top of the outer periphery of the folded part, so that the fastened part is a gap between the electrode winding body and the rectangular hard case. Therefore, even when the electrode winding body expands due to charging / discharging, the end portion and the winding stop portion of each sheet are not pressed against the electrode winding body. As a result, a winding can be obtained in which the pressure applied to the electrode winding body of the wound battery in which the electrode winding body is enclosed in a rectangular hard case is made uniform, and which has a high battery performance and a long life. Type battery.

Furthermore, in the present invention, a winding member that covers the winding ends of the electrode sheet and the separator sheet is provided, and the winding member includes a portion other than the top of the outer periphery of the folded portion of the electrode winding body, and a rectangular hard case. It is desirable to be located in a space defined by the inner surface.
If it does in this way, a winding stop end will be covered by a winding stop member, and each sheet will be stopped. Furthermore, since the winding member is located in a space defined by the outer periphery of the folded portion of the electrode winding body other than the top and the inner surface of the rectangular hard case, the electrode winding body is charged and discharged. Even when it expands, the end of the anti-winding member is not pressed against the electrode winding body.

Furthermore, in the present invention, it is desirable that the winding start ends of the electrode sheet and the separator sheet in the electrode winding body are located on the inner periphery of one folded portion.
In this way, even when the electrode winding body expands due to charging / discharging, the winding start end of each sheet is not pressed against the electrode winding body.

  In addition, a method for manufacturing a wound battery according to the present invention is a method for manufacturing a wound battery having an electrode winding body obtained by winding an electrode sheet and a separator sheet, and a rectangular hard case that houses the electrode winding body. The electrode winding body is wound while the electrode sheet and the separator sheet are wound at the first folded portion, the electrode sheet and the separator sheet are folded while being folded at the first and second folded portions, Created by fastening the outer periphery of the 1st or 2nd folded part at a position other than the top of the head, insert the created electrode winding body into the square hard case, and both tops of the 2nd folded parts And both the outer surfaces of the flat part between them are made into the state which closely_contact | adheres to the inner surface of a square hard case.

  According to the winding type battery manufacturing method of the present invention, the winding start end of each sheet is on the inner periphery of one folded portion, and the winding stop portion of each sheet is on the portion other than the top of the outer periphery of the folded portion, The wound type batteries arranged respectively are easily manufactured.

  According to the wound battery of the present invention and the method of manufacturing the same, the pressure applied to the electrode wound body of the wound battery in which the electrode wound body is sealed in a rectangular hard case is made uniform, and high battery performance is achieved. It has a wound type battery that has a long life and has a manufacturing method thereof.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the present invention is applied to a battery having a wound electrode body sealed in a square can case.

  As shown in FIG. 1, the battery 1 according to the present embodiment is a battery case in which a metal lid 11 is fixed to a metal case 10 and sealed. The case 10 has a flat, substantially quadrangular prism shape, and a lid 11 is provided on one surface other than the flat surface. Two terminals 12, 12 protrude from the lid 11 and are fixed. Further, a flat wound electrode body 20 as shown in FIG. 2 is enclosed in the case 10.

  The electrode body 20 is obtained by winding a positive electrode plate and a negative electrode plate into a flat shape with a separator sheet interposed therebetween. The size of the surface of the case 10 that is represented as the front surface of the hand in FIG. 2 is substantially equal to the size of the wound cross section of the electrode body 20. That is, when the electrode body 20 is inserted into the case 10 and the lid 11 is fixed, the electrode body 20 comes into contact with the inner surfaces of both the case 10 and the lid 11 as shown in FIG. That is, both side surfaces of the flat portion P are in contact with the inner surface of the case 10, and the tops of the upper and lower folded portions R in the figure are in contact with the bottom portion of the case 10 and the inner surface of the lid 11, respectively. Here, FIG. 3 is an AA cross-sectional view of FIG. In this figure, for easy understanding, the positive electrode plate, the negative electrode plate, and the separator sheet are not distinguished and are shown as one sheet as a whole.

  The electrode body 20 is formed by overlapping each sheet and winding it around a flat or elliptical core. As shown in FIG. 3, the wound cross-sectional shape of the wound electrode body 20 is a shape having a flat portion P and folded portions R on both sides (up and down in the drawing). The winding start end 20 a is disposed at the boundary between the folded portion R and the flat portion P of the electrode body 20. In this way, the stepped portion due to the winding start end 20a is not brought into pressure contact with the planar portion of each sheet of the electrode body 20, so that the pressure concentration portion due to the winding start end 20a does not occur.

  Further, the winding end 20b is arranged near the center of the folded portion R in the vertical direction in the drawing. The winding end 20b is fixed to the outermost peripheral surface 21 which is the front peripheral sheet by an insulating tape 22 and is not wound. In the battery 1, the outermost peripheral surface 21 of the electrode body 20 is constituted by a separator sheet in one or more rounds and is insulated from the case 10. Each of the terminals 12 and 12 is electrically connected to either the positive electrode plate or the negative electrode plate of the electrode body 20 and insulated from the other portions. For example, a predetermined insulator is disposed between the terminals 12 and 12 and the lid 11.

  Here, since the inside of the battery 1 formed by the case 10 and the lid 11 has a rectangular parallelepiped shape, and the cross-section of the folded portion R of the electrode body 20 has a substantially semicircular shape, the electrode body 20 does not exist at the four corners. Space S remains. The insulating tape 22 is provided at the center of the space S at the four corners. In FIG. 3, the insulating tape 22 is arranged in the space S at the upper right in the figure, but may be arranged in any space S at the four corners. That is, the insulating tape 22 adheres and fixes the winding end 20b and the outermost peripheral surface 21 and is not in contact with the case 10 or the lid 11. In FIG. 2, the insulating tape 22 is also provided small in the vicinity of the central portion in the width direction of the electrode body 20, but may be provided long along the end portion of the outermost peripheral surface 21.

  When this battery 1 is repeatedly charged and discharged, the electrode body 20 repeatedly expands and contracts. Therefore, the electrode body 20 is deformed inside the case 10 as shown in (a: contraction state) and (b: expansion state) of FIG. Along with this, the size of the space S also changes. Since the insulating tape 22 is provided at the center of the space S, it does not contact the case 10 or the lid 11 in any of the states (a) and (b). Accordingly, the stepped portion due to the end portion of the insulating tape 22 or the winding end end 20b is not pressed against each sheet of the electrode body 20, and therefore no pressure concentration portion occurs.

  Next, a method for manufacturing the battery 1 will be described. First, different active materials are applied to the sheets serving as the bases of the bipolar plates to manufacture positive and negative plates, respectively. Put the manufactured bipolar plate and the sheet sandwiched between the two on the outside and the outside of the plate. At this time, the portion where the end portions of the bipolar plate and the separate sheet are overlapped is the winding start end 20a, and the winding start end 20a is set so as to come to the end of the winding core of the winding machine.

  Next, the winding core is rotated a predetermined number of times at a predetermined speed, and the electrode plate having a predetermined length is wound. Then, the bipolar plates are cut, and only the separator sheet is further wound once or more. Since the ends of the bipolar plates are pressed by the separator sheet, there is no need to perform adhesive fixing or the like. The end portions of the bipolar plates are also arranged in any one of the spaces S. Then, the separator sheet is cut at a position corresponding to the central portion of the space S of the folded portion R and bonded and fixed by the insulating tape 22. This completes the electrode body 20.

  Next, the terminals 12 and 12 are connected to predetermined portions of the electrode body 20. Then, the electrode body 20 is inserted into the case 10 and arranged so that the terminals 12 and 12 protrude from the lid 11, and the lid 11 is fixed to the case 10. Finally, the battery 1 is completed when an electrolyte is injected into the case 10 and sealed.

  The inventor actually manufactured the battery 1 of the present embodiment, and compared the battery performance and life with the comparative example. As the battery 1 of this embodiment, the electrode body 20 is manufactured by winding the separator sheet 3 more times after winding 50 times at an electrode feed speed of 100 mm / min by the above manufacturing method, and enclosing it in a can case Five cases of 1 were produced. Similarly, five batteries of comparative examples in which the winding start end 20a and the winding end end 20b are arranged in the flat portion P were manufactured.

  When these batteries were subjected to a 20 A constant current charge / discharge cycle at 60 ° C., the battery 1 of this embodiment had a life of about 2000 cycles. In contrast, in the comparative example, the service life was reached after about 1500 cycles. In addition, as a result of a 4-ton pressurization test, no abnormalities were observed in the voltage change after the pressurization test for all five of the batteries 1 of this embodiment. On the other hand, in the comparative example, an increase in voltage change was observed in one out of five. From these things, it was confirmed that the battery 1 of this embodiment has a long life and high safety against pressurization.

  As described above in detail, the battery 1 of the present embodiment is obtained by inserting a flat wound electrode body 20 into a rectangular case 10. Since the winding start end 20a of the sheet wound as the electrode body 20 is provided at the boundary between the folded-back portion R and the flat portion P, no pressure is concentrated on a part of the sheet by the winding start end 20a. . Further, since the winding end 20b and the insulating tape 22 are disposed in the space S, the winding end 20b and the insulating tape 22 are not pressed against the electrode body 20 by the case 10 or the lid 11. In particular, by arranging the winding end 20b and the insulating tape 22 in the center of the space S, the electrode body 22 is not pressed even when expanded or contracted, and depending on the end of the winding end 20b or the insulating tape 22. No pressure is applied to a part of the seat. Therefore, the applied pressure applied to the electrode body 20 of the battery 1 in which the wound electrode body is sealed in the rectangular case 10 is made uniform, and the battery 1 having high battery performance and long life can be obtained.

In addition, this form is only a mere illustration and does not limit this invention at all. Therefore, the present invention can naturally be improved and modified in various ways without departing from the gist thereof.
For example, in the above embodiment, the insulation tape 22 is used for winding, but it is also possible to use an adhesive or double-sided tape for winding. In this case, the adhesive application range and the double-sided tape may be attached to the center of the space S.

It is a schematic perspective view which shows schematic structure of the battery of this form. It is a schematic perspective view which shows the electrode body of a battery. It is sectional drawing which shows the electrode body enclosed with the case. It is explanatory drawing which shows the change of the electrode body enclosed with the case.

Explanation of symbols

1 Batteries (winding batteries)
10 Case (square hard case)
20 Electrode body (electrode winding body)
22 Insulation tape (anti-winding member)
P Flat part R Folded part S Space

Claims (4)

In a wound battery having an electrode winding body formed by winding an electrode sheet and a separator sheet, and a rectangular hard case that houses the electrode winding body,
The electrode winding body is a winding method having two folded portions and a flat portion between them,
Both outer top surfaces of the two folded portions of the electrode winding body and both outer surfaces of the flat portion are in close contact with an inner surface of the rectangular hard case;
A wound battery, wherein the electrode sheet and the separator sheet are wound around a portion other than the top of the outer periphery of the folded portion. The wound battery according to claim 1,
A winding member that covers the winding ends of the electrode sheet and the separator sheet;
The winding member is located in a space defined by a portion other than the top of the outer periphery of the folded portion of the electrode winding body and an inner surface of the rectangular hard case. battery. The wound battery according to claim 1 or 2,
A wound battery characterized in that the winding start ends of the electrode sheet and the separator sheet in the electrode winding body are located on the inner periphery of one folded portion. In a method of manufacturing a wound battery comprising: an electrode winding body formed by winding an electrode sheet and a separator sheet; and a rectangular hard case that houses the electrode winding body,
The electrode winding body,
The winding start end of the electrode sheet and the separator sheet is arranged in the first folded portion,
Winding the electrode sheet and the separator sheet while being folded at the first and second folded portions;
Created by fastening at a position other than the top of the outer periphery of the first or second folded portion,
The prepared electrode winding body is inserted into a rectangular hard case, and both the tops of the two folded portions and the flat surfaces between them are in close contact with the inner surface of the rectangular hard case. A method for manufacturing a wound battery.

Images