JP2009199974A - Electrode group for nonaqueous secondary battery, and secondary battery using the same - Google Patents

Abstract

The separator is wound around the outermost periphery of an electrode group with a fixing member, and the outer peripheral surface of the electrode group is covered by at least one turn so that it can be easily inserted into a battery can. Provided is a highly reliable secondary battery electrode group that suppresses breakage, breakage of an electrode plate and falling off of an active material layer, suppresses an internal short circuit, and improves safety as a battery.
A positive electrode plate, a negative electrode plate, and a separator are wound in a spiral shape, and the positive electrode plate, the negative electrode plate, and the separator are wound in a spiral shape. The terminal group 29 of the separator 3 wound around the outermost periphery of the electrode group 6 is covered with the tape 28 at least one turn or more on the outer peripheral surface of the electrode group 6 to constitute the electrode group 6.
[Selection] Figure 2

Description

  The present invention relates to a lithium ion secondary battery typified by a secondary battery, and in particular, a positive electrode plate and a negative electrode plate, which are electrode plates for a secondary battery, are wound around a core via a separator and wound in a spiral shape. The present invention relates to an electrode group for a secondary battery in which an electrode group is formed and a secondary battery using the same.

  In recent years, portable and cordless electronic devices such as AV devices or personal computers and portable communication devices have been rapidly promoted, and these electronic devices are highly reliable as power sources for driving and easy to maintain. Therefore, typical nickel cadmium storage batteries, nickel metal hydride storage batteries, lithium ion secondary batteries, and the like are widely used in various applications.

  In addition, batteries with high-capacity and large-current charge / discharge characteristics are required as driving power sources that require large load characteristics, such as electric tools, bicycles with electric assistance, lawn mowers, and electric vehicles. Development of highly reliable and reliable batteries is demanded. For example, as shown in FIG. 13, an electrode group 107 for a lithium ion secondary battery has a positive electrode plate 101 and a negative electrode plate 102 wound in a spiral shape via a separator 103 and then a part of the outermost periphery of the electrode group 107. Is attached and fixed with a tape 106 so that the electrode group 107 is not loosened. In the electrode group 107, electrode terminals 104 and 105 provided near the tips of the positive electrode plate 101 and the negative electrode plate 102 protrude from both end surfaces of the electrode group 107 to constitute connection terminals.

  Here, as a factor for maintaining and improving the safety for realizing a lithium-ion secondary battery having high capacity and large current charge / discharge characteristics, the positive electrode current collector contains at least a positive electrode active material. A strip-shaped positive electrode plate coated with a coating agent and dried and a strip-shaped negative electrode plate coated with a negative electrode mixture coating material, which is an active material capable of holding lithium, and a negative electrode current collector are swirled with a separator interposed therebetween. There is a demand for a technique in which the outermost periphery of the electrode group is fixed with a tape when the electrode group wound in a shape is inserted into the battery can, and the electrode group is not loosened.

Tape 106 for fixing the terminal portion of separator 103 wound around the outermost periphery of secondary battery electrode group 107 wound in a conventional spiral shape is partially attached with reference to the insertion side into the battery can. Therefore, a manufacturing method has been proposed in which the battery defective rate is reduced by being easily inserted into a battery can (see, for example, Patent Document 1).
JP 05-47419 A

  However, in the prior art of Patent Document 1 described above, as shown in FIG. 13, only the terminal portion of the separator 103 wound around the outermost periphery of the secondary battery electrode group 107 wound in a spiral shape is fixed with the tape 106. In this state, when inserted into the battery can, the separator 103 where the tape 106 is not affixed is broken or broken, causing the positive electrode plate 101 and the negative electrode plate 102 to be damaged or the active material layer to drop off. There is a problem that causes an internal short circuit as a secondary battery.

  The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide an electrode group for a secondary battery in which separators are not turned over or broken, an electrode plate is not damaged, and an active material layer is not dropped.

In order to achieve the above object, the electrode group for a secondary battery of the present invention is applied to a positive electrode current collector coated with a positive electrode mixture containing at least a positive electrode active material and a negative electrode current collector. An electrode group for a secondary battery in which a strip-shaped negative electrode plate and a separator coated with a negative electrode mixture containing an active material capable of holding lithium are spirally wound, and the positive electrode plate, the negative electrode plate, and the separator are spirally wound. The separator wound around the outermost periphery of the rotated electrode group is provided with a fixing member that is wound and fixed at least one turn on the outer peripheral surface of the electrode group.

  According to the present invention, the electrode group is tightly bundled with a fixing member wound tightly for one turn or more, and therefore, when inserted into the battery can, the separator is turned or broken, the electrode plate is damaged, or the active material layer is It is possible to provide a highly safe secondary battery that can prevent dropping and suppress an internal short circuit.

  In the first aspect of the present invention, a strip-shaped positive electrode plate in which a positive electrode current collector is coated with a positive electrode mixture containing at least a positive electrode active material, and a negative electrode current collector containing an active material capable of holding lithium in the negative electrode current collector. An electrode group for a secondary battery in which a strip-shaped negative electrode plate and a separator coated with an agent are wound in a spiral shape, and the positive electrode plate, the negative electrode plate and the separator are wound around the outermost periphery of the electrode group wound in a spiral shape The separator is provided with a fixing member that is wound and fixed at least one turn on the outer peripheral surface of the electrode group, so that the electrode group is tightly bound so as not to loosen and can be inserted into the battery can. Thus, the separator can be turned over or torn when inserted into the battery can, the electrode plate can be prevented from being damaged, and the active material layer can be prevented from falling off, so that an internal short circuit can be suppressed and a highly safe secondary battery can be provided.

  In the second invention of the present invention, the fixing member is provided at least on the insertion side into the battery can, so that the shape on the insertion side can be maintained firmly, thereby improving the insertability into the battery can. In addition, it is possible to provide a highly safe secondary battery that can suppress breakage of the electrode plate and falling off of the active material layer during insertion into the battery can and suppress internal short circuit.

  In the third invention of the present invention, the fixing member is provided at least on the side opposite to the insertion side into the battery can, so that the separator is turned up or broken when inserted into the battery can by holding during insertion. Can be eliminated.

  In the fourth aspect of the present invention, by adopting a configuration in which the fixing member is provided in the central portion of the electrode group, the outer diameter of the electrode group can be made uniform and the insertability into the battery can is improved. be able to.

  In the fifth invention of the present invention, the fixing member is provided so as to cover the entire circumference of the electrode group, so that the electrode group can be tightly bound and maintained in shape so as not to loosen, and the battery can Provides a highly safe rechargeable battery that can be easily inserted into the battery can and can be prevented from turning over or tearing the separator when it is inserted into the battery can, damaging the electrode plate or falling off the active material layer, and preventing internal short circuits. can do.

  In the sixth invention of the present invention, the fixing member is provided in the battery can by providing at least the periphery on the insertion side into the battery can so as to cover one turn or more and a part of the end face on the insertion side. When the battery is inserted, the separator is turned over or broken, the electrode plate is damaged, and the active material layer is prevented from falling off, so that an internal short circuit can be suppressed and a highly safe secondary battery can be provided.

  According to a seventh aspect of the present invention, there is provided an electrode group for a secondary battery in which a method of binding a spirally wound electrode group by using a tape as a fixing member is easy. Can do.

In the eighth invention of the present invention, by using a heat shrinkable tube as the fixing member, the secondary battery electrode group can be instantly bundled using heat and the electrode group is less likely to loosen. Can be provided.

  According to a ninth aspect of the present invention, there is provided an electrode group for a secondary battery in which a coating material is used as a fixing member, so that the electrode group is tightly bound and fixed so as not to loosen with a thin film. Can do.

  In a tenth aspect of the present invention, by forming a secondary battery electrode group and an electrolytic solution according to any one of the first to sixth aspects of the present invention in a battery can, It is possible to provide a highly safe secondary battery that can suppress turning over and tearing of the separator when inserted into the battery can, breakage of the electrode plate and falling off of the active material layer, thereby suppressing internal short circuit.

  The best mode of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an apparatus for manufacturing a secondary battery electrode group according to an embodiment of the present invention. A method for manufacturing a secondary battery electrode group according to an embodiment of the present invention will be described below in detail with reference to FIG.

  First, a strip-like positive electrode plate 1 in which a positive electrode mixture containing at least a positive electrode active material is applied to a positive electrode current collector, and a negative electrode mixture in which a negative electrode mixture containing an active material capable of holding lithium is applied to a negative electrode current collector. 2 and the strip-shaped separator 3a and the separator 3b are respectively disposed in the unwinding portion 13 of the positive electrode plate 1, the unwinding portion 14 of the negative electrode plate 2, the unwinding portion 15 of the separator 3a, and the unwinding portion 16 of the separator 3b in a hoop state. ing. The strip-shaped positive electrode plate 1 coming out from the unwinding portion 13, the strip-shaped negative electrode plate 2 coming out from the unwinding portion 14, the unwinding portion 15, and the strip-shaped separator 3 a and the separator 3 b coming out from the unwinding portion 16 The dancer roller 18 of the positive electrode plate 1, the dancer roller 19 of the negative electrode plate 2, the dancer roller 20 of the separator 3 a, and the dancer roller 21 of the separator 3 b for making the tension at the time of winding constant after being conveyed around , And further passes between the main nip rollers 8, and is then wound in a spiral shape by the winding core 7.

  The main nip roller 8, the electrode plate cutter 23, and the flat plate 22 are arranged in the order of the main nip roller 8, the electrode plate cutter 23, and the flat plate 22 in a direction away from the position of the core 7. The flat plate 22 is disposed in parallel on both sides of the positive electrode plate 1 and the negative electrode plate 2 and is pushed between the main nip rollers 8 with the positive electrode plate 1 and the negative electrode plate 2 interposed therebetween. The electrode plate cutter 23 is arranged perpendicularly to the upper and lower surfaces of the positive electrode plate 1 and the negative electrode plate 2 to cut the positive electrode plate 1 and the negative electrode plate 2.

  Next, the main nip roller 8 is composed of a pair of movable main nip rollers 8a and a fixed main nip roller 8b. The movable main nip roller 8a and the fixed main nip roller 8b are closed when they are in contact with each other, and are opened when they are separated from each other. It is supposed to be.

  In addition, the winding core 7 is configured to rotate in the vicinity of the main nip roller 8. After the positive electrode plate 1 and the separator 3a, and the separator 3b and the negative electrode plate 2 are sandwiched between the pair of main nip rollers 8, the leading ends of the separator 3a and the separator 3b are sandwiched between the core auxiliary pin 7a and the core pin 7b and wound in a spiral shape. Do times. Positive electrode plate 1, negative electrode plate 2, separator 3a, separator 3a wound around the outermost periphery of an electrode group wound in a spiral shape, and fixing member 24 for fixing the terminal portion of separator 3b are fixed members in a hoop state. It arrange | positions at 24 unwinding parts 25. FIG.

After the belt-like fixing member 24 coming out from the unwinding portion 25 passes between the flat plate 26 and the fixing member cutter 27, the fixing member 24 is pasted on the outermost periphery of the spirally wound electrode group for one turn or more.
The fixing member cutter 27 and the flat plate 26 are arranged in the order of the fixing member cutter 27 and the flat plate 26 in a direction away from the position of the core 7. The flat plate 26 is arranged in parallel to both sides of the fixing member 24 and is configured to supply and affix the fixing member 24 to the outermost periphery of the electrode group wound in a spiral shape with the fixing member 24 interposed therebetween. The fixing member cutter 27 is arranged perpendicularly to the upper and lower surface sides of the fixing member 24 to cut the fixing member 24.

  Further, the operation will be described with reference to FIG. 1. After the positive electrode plate 1, the negative electrode plate 2, the separator 3a and the separator 3b are sandwiched between the movable main nip roller 8a and the fixed main nip roller 8b, the core auxiliary pin 7a and the core pin are inserted. 7b comes into contact with each other to form a circular shape, and the separator 3a and separator 3b are sandwiched therebetween, and the winding core 7 is rotated counterclockwise to wind the separator 3a and separator 3b around the winding core 7.

  Thereafter, the movable main nip roller 8a is opened during the rotation of the winding core 7, and the winding core 7 is rotated counterclockwise in the direction of the arrow, whereby the positive electrode plate 1, the negative electrode plate 2, the separator 3a, and the separator 3b are moved. Wind around the core 7. Then, the tension applied to the positive electrode plate 1 and the negative electrode plate 2 is arranged in parallel on both sides of the positive electrode plate 1 and the negative electrode plate 2, and the traveling direction of the positive electrode plate 1 and the negative electrode plate 2 sandwiching the positive electrode plate 1 and the negative electrode plate 2. The positive plate 1 and the negative plate 2 are pressed from the upper and lower surfaces of the positive plate 1 and the negative plate 2 and are moved in parallel in the traveling direction of the positive plate 1 and the negative plate 2. The tension applied to the negative electrode plate 2 is forcibly released, and the positive electrode plate 1 and the negative electrode plate 2 are cut by the electrode plate cutter 23.

  Thereafter, the winding core 7 is rotated counterclockwise in the direction of the arrow to wind the positive electrode plate 1 and the negative electrode plate 2 existing between the winding core 7 and the electrode plate cutter 23, and then the fixing member 24 is sandwiched between the flat plates 26. Then, supply and paste one or more turns to the outermost periphery of the electrode group. Furthermore, after the winding core 7 rotates counterclockwise in the direction of the arrow and stops, it is cut by the fixing member cutter 27. After cutting, the core 7 can be rotated counterclockwise in the state where the fixing member 24 is pressed on the outermost periphery of the electrode group by the flat plate 26 to produce the electrode group. The fixing member 24 is fixed to the outermost periphery of the electrode group for one turn or more, so that the tightness and the outer diameter of the electrode group are maintained and the insertion into the battery can is facilitated. Suppression and tearing, breakage of the electrode plate and falling off of the active material layer can be suppressed to prevent internal short circuit. Hereinafter, specific embodiments of the present invention will be described in more detail, but the present invention is not limited to the following.

  In the first embodiment, as shown in FIG. 1, after the positive electrode plate 1, the negative electrode plate 2, the separator 3a, and the separator 3b are sandwiched between the movable main nip roller 8a and the fixed main nip roller 8b, the core auxiliary pin 7a and the core pin are inserted. 7b comes into contact with each other to form a circular shape, and the separator 3a and the separator 3b are sandwiched therebetween, and the core 7 is rotated counterclockwise at a speed of 1200 revolutions per minute. 3b was wound.

  Thereafter, the movable main nip roller 8a is opened during the rotation of the winding core 7, and the winding core 7 is rotated counterclockwise in the direction of the arrow, whereby the positive electrode plate 1, the negative electrode plate 2, the separator 3a, and the separator 3b are moved. It was wound around the core 7. The traveling direction of the positive electrode plate 1 and the negative electrode plate 2 by pressing the flat plate 22 forcibly releasing the tension interposed between the positive electrode plate 1 and the negative electrode plate 2 from the upper and lower surfaces of the positive electrode plate 1 and the negative electrode plate 2 with a force of 30N. Thus, the tension applied to the positive electrode plate 1 and the negative electrode plate 2 was forcibly released, and the positive electrode plate 1 and the negative electrode plate 2 were cut by the electrode plate cutter 23.

After that, after winding the positive electrode plate 1 and the negative electrode plate 2 existing between the winding core 7 and the electrode plate cutter 23 by winding the winding core 7 counterclockwise at a speed of 1200 rotations per minute. The fixing member 24 is attached to the end portion of the separator 3a and the separator 3b wound around the outermost periphery of the electrode group.
It was moved at a speed of 100 mm / sec in the direction approaching the outermost periphery of the electrode group sandwiched between 6 and wound in a spiral shape, and pressed and applied with a force of 1 N for 1 turn or more. Further, the core 7 was rotated counterclockwise at a rotation speed of 1200 rotations per minute and stopped, and then cut by the fixing member cutter 27 to produce an electrode group.

  Next, as an electrode group for a lithium secondary battery having a diameter of 18 mm and a height of 65 mm, a positive electrode mixture paint containing at least a positive electrode active material was applied to an aluminum current collector and dried. A width of 58.5 mm and a thickness of 0.2 mm were obtained by applying and drying a negative electrode mixture paint containing an active material capable of holding lithium on a strip-like positive electrode plate having a width of 57 mm and a thickness of 0.2 mm and a copper current collector. An electrode group is formed by winding a belt-shaped negative electrode plate with a separator having a width of 62 mm and a thickness of 0.02 mm interposed therebetween.

  As shown in FIG. 2 (a), the electrode group according to the present invention has a linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group, with a tape 28 as a fixing member. Covered and fixed for more than a turn. The tape 28 used was a polyester-based support having a thickness of 0.025 mm and a silicon-based adhesive. Further, as shown in FIG. 2B, the tape 28 is positioned 0.5 to 1 mm away from the end face of the separator 28 on the side that first encounters the battery can 32 when inserted into the battery can 32. An electrode group produced by attaching the outer end face of the tape 28 together and covering the tape 28 for one turn or more was designated as Example 1.

  In the second embodiment, parts different from the first embodiment will be described with reference to FIGS. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 3 (b), a tape 28 as a fixing member is fixed into the battery can 32 for fixing the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. The first separator end face encountered with the battery can 32 at the time of insertion is used as a reference, and the outer end face of the tape 28 is placed at a position 0.5 to 1 mm away from the end face to cover and cover one or more turns. The electrode group was defined as Example 2.

  In the third embodiment, parts different from the first embodiment will be described with reference to FIG. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 4, a tape 28 as a fixing member is fixed to the center of the electrode group by one turn for fixing the linear terminal portion 29 positioned in the longitudinal direction of the separator 3 wound around the outermost periphery of the electrode group. An electrode group produced by covering and pasting was designated as Example 3.

  In the fourth embodiment, parts different from the first embodiment will be described with reference to FIGS. 5 (a) and 5 (b). About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 5B, a wide tape 28 as a fixing member is fixed in the battery can to fix the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. The separator end face that first encounters the battery can at the time of insertion into the reference is taken as a reference, and the separator end face that is 0.5 to 1 mm away from the end face and the opposite separator end face that first encounters the battery can is taken as the reference and zero from the end face. An electrode group produced by aligning the outer end face of the wide tape 28 at a position 5 to 1 mm apart and covering and affixing it for one turn or more was taken as Example 4.

In the fifth embodiment, parts different from the first embodiment will be described with reference to FIG. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 6, the linear terminal part 29 located in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group.
When the heat-shrinkable tube 30 as a fixing member made of a cylindrical polyethylene material is inserted into the battery can, the separator end face that first encounters the battery can is used as a reference, and the inner position from the end face is fixed. The heat shrinkable tube 30 was inserted into the tube, and further cut at a position of 2 to 3 mm from the end face to the opposite side, and then heat was applied to shrink the heat shrinkable tube 30 to cover the outermost periphery of the electrode group and a part of the end face. An electrode group was defined as Example 5.

  In the sixth embodiment, parts different from the first embodiment will be described with reference to FIGS. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. FIG. 7A shows that at least a coating material 31 as a fixing member is inserted into the battery can for fixing the linear terminal portion 29 positioned in the longitudinal direction of the separator 3 wound around the outermost periphery of the electrode group. The electrode group produced by applying and covering one or more turns on the outer peripheral surface on one side is shown. FIG. 7B shows that the coating material 31 is at least one turn on the outer peripheral surface on the insertion side into the battery can and the coating material 31 is one turn or more on the outer peripheral surface of the central portion of the electrode group. An electrode group produced by coating and covering is shown.

  FIG. 7 (c) shows that the coating material 31 is at least one turn on the outer peripheral surface on the insertion side into the battery can and the coating material 31 is one turn or more on the outer peripheral surface of the central portion of the electrode group. And the electrode group produced by coating the coating material 31 on the outer peripheral surface opposite to the insertion side into the battery can and covering it at one place for one turn or more is shown. FIG. 7D shows that the coating material 31 is at least one turn on the outer peripheral surface on the insertion side into the battery can and one coating material 31 on the outer peripheral surface opposite to the insertion side in the battery can. An electrode group produced by applying and covering at least one turn is shown. The coating material 31 has a configuration in which polyethylene, pyropropylene, polyvinyl chloride, polyester, polyimide, and a fluororesin-based material desirable for the electrolytic solution are applied to the outer peripheral surface of the electrode group, and then cooled and dried. ing. The electrode group shown in FIGS. 7A to 7D described above was taken as Example 6.

  In the seventh embodiment, parts different from the first embodiment will be described with reference to FIGS. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. FIG. 8A shows a case where a tape 28 having a width of 9 mm as a fixing member is fixed in the battery can to fix the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. The separator end face that first encounters the battery can at the time of insertion is used as a reference, and the outer end face of the tape 28 is aligned at a position 0.5 to 1 mm away from the end face, and at least one turn is covered and pasted. An electrode group is shown. FIG. 8 (b) shows the outer surface of the tape 28 at a position 0.5 to 1 mm away from the end face of the separator that first encounters the battery can when the tape 28 having a width of 9 mm is inserted into the battery can. An electrode group produced by covering and pasting at least one turn or more and covering one end of one turn or more on the outer peripheral surface of the central portion of the electrode group is shown.

FIG. 8 (c) shows the outer side of the tape 28 at a position 0.5 to 1 mm away from the end face of the separator that first encounters the battery can when the tape 28 having a width of 9 mm is inserted into the battery can. Combine the end faces, at least one turn or more, and one center or more on the outer peripheral surface of the center of the electrode group, the separator end face on the opposite side that first encounters the battery can when inserted into the battery can The electrode group produced by aligning the outer end face of the tape 28 at a position 0.5 to 1 mm away from the end face thereof and covering and attaching one turn or more at one place. FIG. 8 (d) shows the separator 28 that first encounters the battery can when the tape 28 having a width of 9 mm is inserted into the battery can, and the outside of the tape 28 is positioned 0.5 to 1 mm away from the end face. Tape at a position 0.5 to 1 mm away from the end face, with the end faces aligned and at least one turn or more as a reference and the separator end face on the opposite side that first encounters the battery can when inserted into the battery can. The electrode group produced by covering and attaching one or more turns in one place together with the outer end faces of 28 is shown. The electrode group shown in FIGS. 8A to 8D described above was taken as Example 7.

  In the eighth embodiment, portions different from the first embodiment will be described with reference to FIGS. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. FIG. 9A shows a cylindrical heat shrinkable tube 30 having a width of 9 mm as a fixing member for fixing the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. After inserting at least one place in the center of the group, when inserting the battery can into the battery can, the heat shrink tube 30 is inserted at a position 10 mm away from the end face of the separator first encountered with the battery can. 3 shows an electrode group produced by cutting at a position of 2 to 3 mm on the opposite side and then applying heat to shrink the heat-shrinkable tube 30 to cover the outermost periphery and a part of the end face of the electrode group.

  FIG. 9 (b) shows a cylindrical heat-shrinkable tube 30 having a width of 9 mm, one in the center of the electrode group, and the separator end face on the opposite side that first encounters the battery can when inserted into the battery can. After one insertion at a position 0.5 to 1 mm away from the end face, when shrinking into the battery can, the separator end face that first encounters the battery can is used as a reference, and heat shrinks to a position 10 mm away from the end face. After the tube 30 is inserted and cut at a position of 2 to 3 mm on the opposite side from the end face, the heat shrinkable tube 30 is shrunk by applying heat to cover the outermost periphery of the electrode group and a part of the end face. Show. FIG. 9 (c) shows the same separator-shaped end face that first encounters the battery can when the heat-shrinkable tube 30 having a cylindrical width of 9 mm is inserted into the battery can, and is 0.5 to 1 mm from the end face. Insert the heat shrink tube 30 at a position 10 mm away from the end face of the separator that is first encountered with the battery can when it is inserted into the battery can after being inserted at one position away from the end, and further away from the end face. An electrode group is shown which is cut at a position of 2 to 3 mm on the side and then heat is applied to shrink the heat-shrinkable tube 30 so as to cover a part of the outermost periphery and end face of the electrode group. The electrode group shown in FIGS. 9A to 9C described above is referred to as Example 8.

  In the ninth embodiment, parts different from the first embodiment will be described with reference to FIG. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 10, a cylindrical wide heat-shrinkable tube 30 is used as a fixing member to fix the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. At the time of insertion into the inside, with the separator end face on the opposite side first encountering the battery can as a reference, after inserting the outer end face of the wide heat shrink tube 30 at a position 0.5 to 1 mm away from the end face, An electrode group prepared by cutting at a position of 2 to 3 mm from the end surface to the opposite side and then applying heat to contract the wide heat shrinkable tube 30 to cover the outermost periphery of the electrode group and a part of the end surface was taken as Example 9. .

  In the tenth embodiment, parts different from the first embodiment will be described with reference to FIG. About other contents, it is equivalent to the manufacturing method of the electrode group for secondary batteries given in Example 1. As shown in FIG. 11, a coating material 31 as a fixing member is fixed to the entire circumferential surface of the electrode group for fixing the linear terminal portion 29 positioned in the vertical direction of the separator 3 wound around the outermost periphery of the electrode group. An electrode group produced by coating and covering was designated as Example 10.

The electrode group 6 described in Examples 1 to 10 was housed in a battery can 32 as shown in FIG. Insulators 33 are provided on both upper and lower end faces of the electrode group 6, and the positive electrode plate electrode terminal 4 made of aluminum is led out from the positive electrode plate 1 and welded to the battery lid 34, and the negative electrode plate electrode terminal 5 made of nickel. Was led out from the negative electrode plate 2 and welded to the battery can 32. An electrolyte was injected into the battery can 32. The battery lid 32 was fixed by caulking the battery can 32 through the gasket 35 having the surface coated with asphalt, and the airtightness in the battery can 32 was maintained. A secondary battery manufactured with the above configuration was taken as Example 11.

(Comparative example)
As shown in FIG. 13, an electrode group 107 in which only the terminal portion of the separator 103 wound around the outermost periphery of the secondary battery electrode group 107 wound in a spiral shape was fixed with a tape 106 was used as a comparative example. In order to compare the electrode group of the comparative example and the electrode group of the example in the present invention, the occurrence rate of breakage of the electrode plate and dropping of the active material layer when the electrode group was inserted into the battery can was evaluated.

  The rate of occurrence of electrode plate breakage and active material layer dropout is the number of defective electrode plate breakage and active material layer dropout for 1 million pieces constructed in the process of inserting the electrode group into the electrode can. The ratio with the number of inspections is defined as the incidence rate, and if the electrode group is disassembled and the electrode plate is broken and the active material layer is not dropped using an optical microscope, the non-defective product, the electrode plate is broken, and the active material layer is dropped Products were selected as defective products, and the quantity of defective products due to electrode plate breakage and loss of active material layer was compared. Comparative data of the secondary battery electrode group of the comparative example and the secondary battery electrode group of the present invention are shown in Table 1.

  First, the electrode group of the present invention is provided with a fixing member that is wound and fixed at least one turn on the outer peripheral surface of the electrode group, so that the separator is turned up or broken when inserted into the battery can. It is possible to provide a highly safe secondary battery that can suppress internal damage and dropout of the active material layer and suppress internal short circuits. From the results of (Table 1), the electrode group for secondary batteries of the present invention has a unique effect of constructing a battery with higher safety by reducing defects due to breakage of the electrode plate and dropping of the active material layer. is doing. In particular, in Examples 5, 8, and 9, as shown in FIGS. 6, 9, and 10, the insertion side into the battery can was covered with one turn or more and a part of the end surface was covered with a heat-shrinkable tube. With this configuration, the electrode group is tightly bound so as not to loosen, and the insertion property into the battery can is improved. When inserted into the battery can, the separator is turned over or broken, and the electrode plate is damaged or activated. It is excellent in reducing defects by suppressing the falling off of the material layer.

On the other hand, in the case of the comparative example, in the state in which only the terminal portion of the separator 103 wound around the outermost periphery of the secondary battery electrode group 107 wound in a spiral shape as shown in FIG. When inserted into the can, the portion of the separator 103 where the tape 106 is not attached is turned over or torn, the positive electrode plate 101 and the negative electrode plate 102 are damaged, and the active material layer is dropped, causing an internal short circuit as a battery. There's a problem. In addition, in the state where only the terminal portion of the separator 103 is fixed with the tape 106, there is a possibility that the electrode group is loosened, the diameter of the electrode group is increased by loosening, and the separator 103 is turned over or torn when inserted into the battery can. There is a problem in that the positive electrode plate 101 and the negative electrode plate 102 are damaged and the active material layer is detached.

  As described above in Examples 1 to 10, according to the electrode group for a secondary battery of the present invention, the tightness at the time of winding of the electrode group is covered by covering at least one turn of the outer peripheral surface of the electrode group. Maintain the degree and outer diameter, and it is easy to insert into the battery can, and the separator can be prevented from being turned over or torn, the electrode plate can be damaged or the active material layer can be removed, and internal short circuit can be prevented. A high secondary battery could be realized.

  The electrode group for a secondary battery according to the present invention is wound around at least one turn on the outer peripheral surface of the electrode group on the separator wound around the outermost electrode group in which the positive electrode plate, the negative electrode plate, and the separator are wound in a spiral shape. By providing a fixing member that is attached and fixed, the separator is turned over and torn when inserted into the battery can, the electrode plate is damaged, and the active material layer is prevented from falling off. High-capacity secondary batteries can be obtained, and it is possible to avoid heat-causing events due to internal short circuits, and it is excellent in safety. It is useful as a portable power source.

The schematic diagram which shows the manufacturing apparatus of the electrode group for secondary batteries in one embodiment of this invention (A) The perspective view of the electrode group for secondary batteries in the form of Example 1 of this invention, (b) The schematic diagram seen from the outer peripheral surface of the electrode group for secondary batteries in the form of Example 1 (A) The perspective view of the electrode group for secondary batteries in the form of Example 2 of this invention, (b) The schematic diagram seen from the outer peripheral surface of the electrode group for secondary batteries in the form of Example 2 The perspective view of the electrode group for secondary batteries in the form of Example 3 of the present invention. (A) The perspective view of the electrode group for secondary batteries in the form of Example 4 of this invention, (b) The schematic diagram seen from the outer peripheral surface of the electrode group for secondary batteries in the form of the Example 4 The perspective view of the electrode group for secondary batteries in the form of Example 5 of this invention (A) The perspective view of the electrode group for secondary batteries in the form of Example 6 of this invention, (b) The perspective view of the electrode group for secondary batteries in another form of the Example 6, (c) The Example The perspective view of the electrode group for secondary batteries in another form of 6th, (d) The perspective view of the electrode group for secondary batteries in another form of the Example 6 (A) The perspective view of the electrode group for secondary batteries in the form of Example 7 of this invention, (b) The perspective view of the electrode group for secondary batteries in another form of the Example 7, (c) The Example 7 is a perspective view of a secondary battery electrode group in another form of FIG. 7, (d) a perspective view of a secondary battery electrode group in another form of Example 7; (A) The perspective view of the electrode group for secondary batteries in the form of Example 8 of this invention, (b) The perspective view of the electrode group for secondary batteries in another form of the Example 8, (c) The Example The perspective view of the electrode group for secondary batteries in another form of 8 The perspective view of the electrode group for secondary batteries in the form of Example 9 of this invention The perspective view of the electrode group for secondary batteries in the form of Example 10 of this invention. Partially cutaway perspective view showing a typical lithium ion secondary battery The perspective view of the electrode group for secondary batteries in the conventional manufacturing method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode plate 2 Negative electrode plate 3 Separator 3a Separator 3b Separator 4 Electrode terminal for positive electrode plates 5 Electrode terminal for negative electrode plates 6 Electrode group 7 Winding core 7a Winding auxiliary pin 7b Winding pin 8 Main nip roller 8a Movable main nip roller 8b Fixed main nip roller DESCRIPTION OF SYMBOLS 13 Unwinding part 14 Unwinding part 15 Unwinding part 16 Unwinding part 17 Traveling roller 18 Dancer roller 19 Dancer roller 20 Dancer roller 21 Dancer roller 22 Flat plate 23 Electrode plate cutter 24 Fixing member 25 Unwinding part 26 Flat plate 27 Fixed member Cutter 28 Tape 29 Terminal 30 Heat shrinkable tube 31 Coating material 32 Battery can 33 Insulator 34 Battery lid 35 Gasket

Claims (10)

  A strip-like positive electrode plate in which a positive electrode mixture containing at least a positive electrode active material is applied to a positive electrode current collector, and a strip-like negative electrode plate and a separator in which a negative electrode mixture containing an active material capable of holding lithium is applied to a negative electrode current collector The electrode group for a secondary battery wound in a spiral shape, wherein the positive electrode plate, the negative electrode plate, and the separator are wound around the outermost periphery of the electrode group wound in a spiral shape. An electrode group for a secondary battery, comprising a fixing member that is wound and fixed around at least one turn on the outer peripheral surface.   The secondary battery electrode group according to claim 1, wherein the fixing member is provided at least on an insertion side into the battery can.   The secondary battery electrode group according to claim 1, wherein the fixing member is provided at least on the side opposite to the insertion side into the battery can.   The secondary battery electrode group according to claim 1, wherein the fixing member is provided in a central portion of the electrode group.   The secondary battery electrode group according to claim 1, wherein the fixing member is provided so as to cover the entire circumference of the electrode group.   2. The electrode group for a secondary battery according to claim 1, wherein the fixing member is provided so that at least a peripheral surface on the insertion side into the battery can covers at least one turn and a part of an end surface on the insertion side.   The secondary battery electrode group according to claim 1, wherein a tape is used as the fixing member.   The electrode group for a secondary battery according to claim 1, wherein a heat shrinkable tube is used as the fixing member.   The secondary battery electrode group according to claim 1, wherein a coating material is used as the fixing member.   The secondary battery formed by sealing the electrode group for secondary batteries and electrolyte solution as described in any one of Claims 1-6 in a battery can.

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