JP6578818B2 - Manufacturing method of secondary battery - Google Patents

Description

  The present invention relates to a method for manufacturing a secondary battery. More specifically, the present invention relates to a method for manufacturing a secondary battery having a wound electrode body in which positive and negative electrode plates are wound with a separator interposed therebetween.

  A wound-type electrode body used in a general secondary battery or the like is wound with positive and negative electrode plates each having an active material layer formed on both sides, with a separator interposed therebetween. It is manufactured by. In the wound electrode body, the negative electrode plate is positioned on the outer peripheral side of the positive electrode plate. For this reason, in the wound electrode body, there is no positive electrode plate facing the outermost peripheral surface, which is the outer peripheral surface of the outermost part of the negative electrode plate.

  And, in a secondary battery in which a wound electrode body is housed in a battery case together with an electrolyte solution, when this is charged and discharged, the outermost peripheral surface of the negative electrode plate has no positive electrode plate facing it. , Reacts with the portion of the positive electrode plate that is close to the outermost peripheral surface of the negative electrode plate. However, the portion of the positive electrode plate that reacts with the outermost peripheral surface of the negative electrode plate naturally faces the portion on the inner peripheral side with respect to the outermost peripheral surface of the negative electrode plate, and thus reacts with the portion of the negative electrode plate that faces the negative electrode plate. . As a result, the reaction of the positive electrode plate portion that reacted with the outermost peripheral surface of the negative electrode plate may become excessive compared to the other portions. Such excessive reaction is preferably not caused as much as possible. This is because a part of the metal constituting the positive electrode active material may be eluted at the portion of the positive electrode plate that has reacted excessively during charging.

  For example, Patent Document 1 describes a method for manufacturing a non-aqueous electrolyte secondary battery in which initial charging and aging are performed in a state where an amount of an electrolyte solution that can be held in a wound body is injected. As a result, the amount of the electrolyte that contacts the outermost peripheral surface of the negative electrode plate in the wound body can be reduced as much as possible. Therefore, the charging reaction on the outermost peripheral surface of the negative electrode plate during initial charging can be suppressed, and It is said that elution of the positive electrode active material during aging can be suppressed.

JP, 2014-116179, A

  However, in the above prior art, an electrolytic solution is added to the battery case after aging. For this reason, when the secondary battery is used after the electrolytic solution is added, there is an amount of electrolytic solution that can charge and discharge the outermost peripheral surface of the negative electrode plate. Therefore, during charging / discharging when the secondary battery is used, the outermost peripheral surface of the negative electrode plate may react with the positive electrode plate, and the reaction of the positive electrode plate may become excessive.

  The present invention has been made for the purpose of solving the problems of the prior art described above. That is, the problem is to provide a method for manufacturing a secondary battery in which excessive reaction of the positive electrode during charging and discharging is suppressed.

In order to solve this problem, the method for producing a secondary battery according to the present invention includes an electrode body and an electrolyte solution obtained by winding a positive electrode plate, a negative electrode plate, and a separator in a battery case . The outer peripheral surface is a flat portion having a flat surface and the outer peripheral surface is a curved surface portion. The electrode body has a negative electrode plate on the outer peripheral side of the positive electrode outermost peripheral portion located on the outermost periphery of the positive electrode plate. A secondary battery having a negative electrode outer peripheral side negative electrode portion wound at a position and a separator having a negative electrode outer peripheral side separator portion wound at a position on the outer peripheral side of the positive electrode outer peripheral side negative electrode portion. In the manufacturing method, the positive electrode plate, the negative electrode plate and the separator are unwound from the respective unwinding positions, and the positive electrode plate and the negative electrode plate are wound at the winding position with the separator interposed therebetween. To produce the electrode body An electrode body manufacturing process, and an assembly process for housing the electrode body in the battery case and injecting an electrolyte into the battery case. In the electrode body manufacturing process, from the unwinding position of the separator to the winding position A part of the separator that becomes the negative electrode outer peripheral separator part and at least a part of the part located on the curved surface part is heated to a melting point or higher. is there.

In the method for manufacturing a secondary battery according to the present invention, in the electrode body manufacturing step, at least a part of the separator that is to be the negative electrode outer side separator part and located on the curved surface part is heated to the melting point or higher. For this reason, in the secondary battery, the amount of the electrolyte solution retained is reduced at the heating location in the separator on the outer periphery of the negative electrode. Thereby, at the time of charge / discharge of the secondary battery, reaction on the outer peripheral surface of the positive electrode outer peripheral side negative electrode portion of the negative electrode plate is suppressed. Therefore, the excessive reaction of the positive electrode during charging / discharging is suppressed at the curved surface portion of the electrode body where the excessive reaction is likely to occur .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the secondary battery by which the excessive reaction of the positive electrode at the time of charging / discharging was suppressed is provided.

It is sectional drawing of the battery which concerns on this form. It is a perspective view of an electrode body. It is a figure for demonstrating the overlap of the negative electrode plate in a electrode body, a positive electrode plate, and a separator about the width direction. It is a figure for demonstrating the stacking | superposition of the negative electrode plate, positive electrode plate, and separator in an electrode body about a longitudinal direction. It is a schematic block diagram of a winding apparatus. It is sectional drawing of the separator used with a 2nd form.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best mode for embodying the present invention will be described in detail with reference to the drawings. In this embodiment, the present invention is applied to a method for manufacturing a lithium ion secondary battery.

[First embodiment]
First, the battery 100 (refer FIG. 1) manufactured by the manufacturing method of the secondary battery which concerns on this form is demonstrated. FIG. 1 is a cross-sectional view of a battery 100 according to this embodiment. As shown in FIG. 1, the battery 100 is a lithium ion secondary battery in which an electrode body 110 and an electrolytic solution 120 are accommodated in a battery case 130. The electrolytic solution 120 is made of an organic solvent in which a lithium salt is dissolved. The battery case 130 includes a case main body 131 and a sealing plate 132. In addition, the sealing plate 132 includes an insulating member 133.

  FIG. 2 is a perspective view of the electrode body 110. As shown in FIG. 2, the electrode body 110 of the present embodiment is a flat wound electrode body. FIG. 3 is a diagram for explaining the superposition of the negative electrode plate N, the positive electrode plate P, and the separator S that constitute the electrode body 110. In FIG. 3, the up-down direction is the longitudinal direction of the negative electrode plate N, the positive electrode plate P, and the separator S, and the left-right direction is the width direction. The electrode body 110 shown in FIG. 2 has a negative electrode plate N, a positive electrode plate P, and two separators S as shown in FIG. It is molded into a flat shape by pressing.

  The separator S of this embodiment is a single layer. As a material of the separator S of this embodiment, for example, polypropylene (PP), polyethylene (PE), or the like can be used.

  The negative electrode plate N is formed by forming a negative electrode active material layer N2 on both surfaces of a negative electrode current collector foil N1 with a negative electrode material such as a negative electrode active material or a binder. The negative electrode plate N has a portion where the negative electrode active material layer N2 is formed and a portion where it is not formed. In FIG. 3, with respect to the negative electrode plate N, the portion where the negative electrode active material layer N2 is formed is dot-hatched. Further, the negative electrode current collector foil N1 is exposed in a portion where the negative electrode active material layer N2 is not formed.

  The positive electrode plate P is formed by forming a positive electrode active material layer P2 with a positive electrode material such as a positive electrode active material or a binder on both surfaces of the positive electrode current collector foil P1. The positive electrode plate P has a portion where the positive electrode active material layer P2 is formed and a portion where the positive electrode active material layer P2 is not formed. In FIG. 3, with respect to the positive electrode plate P, the portion where the positive electrode active material layer P2 is formed is subjected to dot hatching. Further, the positive electrode current collector foil P1 is exposed in a portion where the positive electrode active material layer P2 is not formed.

  That is, as shown in FIG. 3, both the negative electrode plate N and the positive electrode plate P are wound in a state where they are overlapped with the separator S in the portions where the negative electrode active material layer N2 and the positive electrode active material layer P2 are formed. The Therefore, the central portion 111 of the electrode body 110 shown in FIG. 2 is a portion where the negative electrode plate N, the positive electrode plate P, and the separator S overlap.

  On the other hand, as shown in FIG. 3, the exposed portion of the negative electrode current collector foil N <b> 1 of the negative electrode plate N protrudes to the right in the width direction from the separator S. The exposed portion of the positive electrode current collector foil P1 of the positive electrode plate P protrudes to the left in the width direction from the separator S. For this reason, the electrode body 110 in FIG. 2 showing the wound state has a negative electrode end portion 112 that is a portion made only of the negative electrode current collector foil N1 and a positive electrode end portion 113 that is a portion made only of the positive electrode current collector foil P1. , On both the left and right sides of the central portion 111.

  In the battery 100 shown in FIG. 1, a negative electrode terminal 150 is connected to the negative electrode end 112 of the electrode body 110, and a positive electrode terminal 160 is connected to the positive electrode end 113. In addition, the negative electrode terminal 150 and the positive electrode terminal 160 have their ends not connected to the electrode body 110 protruding outside the battery case 130 via the insulating member 133. The battery 100 is charged and discharged at the central portion 111 of the electrode body 110 via the negative electrode terminal 150 and the positive electrode terminal 160. Specifically, the battery 100 is held in the pores of the separator S, which is a porous member, between the negative electrode plate N and the positive electrode plate P located at the central portion 111 of the electrode body 110 during charging and discharging. Lithium ions are exchanged through the electrolytic solution 120.

  FIG. 4 is a view for explaining the superposition of the negative electrode plate N, the positive electrode plate P, and the separator S in the electrode body 110 in the longitudinal direction. That is, FIG. 4 shows a state in which the negative electrode plate N, the positive electrode plate P, and the two separators S are extended in the longitudinal direction by unwinding the electrode body 110. In FIG. 4, the left-right direction is the longitudinal direction of the negative electrode plate N, the positive electrode plate P, and the separator S. The electrode body 110 is formed by winding the negative electrode plate N, the positive electrode plate P, and the separator S of FIG. 4 in the direction of arrow A from the left winding start end. For this reason, the portion on the left side closer to the winding start end is the portion located on the inner peripheral side in the wound electrode body 110.

  As shown in FIG. 4, the electrode body 110 of the present embodiment uses the same length as the two separators S. Both of the two separators S are longer in the longitudinal direction than the negative electrode plate N and the positive electrode plate P. Further, the negative electrode plate N has a longer length in the longitudinal direction than the positive electrode plate P.

  Further, as shown in FIG. 4, when the electrode bodies 110 are overlapped, the winding start side ends of the negative electrode plate N and the positive electrode plate P are aligned. Further, both the winding start sides of the two separators S protrude leftward in FIG. 4 by a length B from the winding start side ends of the negative electrode plate N and the positive electrode plate P. The protruding portion on the winding start side of the separator S is shown as a winding start side separator portion SB in FIG.

  Furthermore, the winding end side of the negative electrode plate N that is longer than the positive electrode plate P projects rightward from the end of the positive electrode plate P on the winding end side by the length C. In addition, both the winding end sides of the two separators S protrude to the right by a length D from the end of the negative electrode plate N on the winding end side. That is, the winding end side of the separator S protrudes rightward from the end of the positive electrode plate P on the winding end side by the length of the length C and the length D.

  In the electrode body 110 wound in the direction of the arrow A in the overlapping state in FIG. 4, the portion on the winding end side of the negative electrode plate N indicated by the length C is more than the outermost peripheral portion of the positive electrode plate P. Is wound around the outer periphery. In FIG. 4, a portion of the negative electrode plate N wound around the outer peripheral side of the outermost peripheral portion of the positive electrode plate P is shown as a positive electrode outer peripheral side negative electrode portion NC.

  In this embodiment, the length C of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is a length that makes one turn at the winding position of the positive electrode outer peripheral side negative electrode portion NC in the electrode body 110. For this reason, the positive electrode outer peripheral side negative electrode part NC is the outermost part of the negative electrode plate N. Further, in the electrode body 110, the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is wound once around the outer peripheral side of the outermost peripheral portion of the positive electrode plate P. Therefore, in the electrode body 110, the opposing positive electrode plate P does not exist on the outer peripheral surface (the lower surface in FIG. 4) of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N.

  Further, in the electrode body 110, the part indicated by SC in FIG. 4 of the separator S is a part wound around the outer peripheral side of the positive electrode outer peripheral side negative electrode part NC of the negative electrode plate N. Further, the part indicated by SD in FIG. 4 of the separator S is a part wound further to the outer peripheral side than the part indicated by SC of the separator S. For this reason, the SD portion of the separator S is also a portion that is wound more on the outer peripheral side than the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N. Therefore, in FIG. 4, a portion obtained by combining the portion indicated by SC and the portion indicated by SD of the separator S is shown as a negative electrode outer peripheral separator portion SCD.

  Here, at the time of charging / discharging of the battery 100, it is preferable that the reaction does not occur so much on the outer peripheral surface of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N because the opposing positive electrode plate P does not exist. The portion of the positive electrode plate P that has reacted with the outer peripheral surface of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N during charging and discharging also reacts with the portion of the negative electrode plate N that is opposed to the inner peripheral side of the positive electrode outer peripheral side negative electrode portion NC. ing. For this reason, the portion of the positive electrode plate P that has reacted with the outer peripheral surface of the negative electrode portion NC on the positive electrode outer peripheral side of the negative electrode plate N is excessively charged and discharged.

  And in order to suppress the reaction at the time of charging / discharging in the outer peripheral surface of the positive electrode outer peripheral side negative electrode part NC of the negative electrode plate N, the separator S wound around the outer peripheral side from the positive electrode outer peripheral side negative electrode part NC of the negative electrode plate N It is preferable to reduce the amount of the electrolytic solution 120 held in the negative electrode outer peripheral separator portion SCD. This is because the reaction at the time of charging / discharging occurs through the electrolytic solution 120 held in the separator S which is a porous member.

  Therefore, in the battery 100 of the present embodiment, the outer peripheral surface of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is reduced by reducing the amount of the electrolyte 120 held in the negative electrode outer peripheral separator portion SCD of the separator S in the electrode body 110. The reaction is suppressed. Specifically, when the electrode body 110 is wound, the portion of the separator S that becomes the negative electrode outer peripheral side separator portion SCD is closed, so that the amount of the electrolyte 120 held in the portion is reduced. ing.

  Next, a method for manufacturing the electrode body 110 of this embodiment will be described. In FIG. 5, schematic structure of the electrode winding apparatus 1 of this form is shown. As described above, the electrode body 110 is formed into a flat shape by winding the negative electrode plate N, the positive electrode plate P, and the two separators S into a cylindrical shape, and then pressing the cylindrical wound member in the radial direction. It has been done. And the electrode winding apparatus 1 shown in FIG. 5 winds the positive electrode plate P, the negative electrode plate N, and the two separators S in a cylindrical shape, and continuously forms the wound body before being formed into a flat shape. It is an apparatus that can be manufactured.

  As shown in FIG. 5, the electrode winding apparatus 1 unwinds a negative electrode unwinding portion 11 for unwinding the negative electrode plate N, a positive electrode unwinding portion 12 for unwinding the positive electrode plate P, and two separators S. Separator unwinding portions 13 and 14 are provided. Then, the negative electrode plate N, the positive electrode plate P, and the two separators S that are unwound from the respective unwinding portions are conveyed toward the winding portion 70 and are wound by the winding portion 70 at the winding position Y on the outer periphery thereof. By being wound up, a cylindrical wound body is obtained.

  The winding portion 70 is for winding the negative electrode plate N, the positive electrode plate P, and the two separators S by rotating in the direction of the arrow X at the position shown in FIG. In addition, as with the winding unit 70, the negative electrode plate N, the positive electrode plate P, and the two separators S are also wound up on the winding unit 71 arranged on the material unwinding unit side with respect to the winding unit 70. Is for. However, the winding part 71 shown in FIG. 5 does not rotate for winding at that position. The winding part 70 and the winding part 71 both rotate and move in the direction of the arrow Z, and their positions can be interchanged by the rotational movement. And the winding part 71 performs the rotation for winding up the negative electrode plate N, the positive electrode plate P, and the two separators S in the position of the winding part 70 which carried out the rotational movement of replacement | exchange from the position shown in FIG.

  Further, each of the winding parts 70 and 71 is divided into two with a plane parallel to the rotation axis as a dividing surface, and a gripping state in which these are pressed against each other and a gripping in which a gap is formed by releasing the gripping The release state can be taken. And the winding parts 70 and 71 rotate in the holding state which hold | gripped the edge which becomes the inner peripheral side in the winding body of the negative electrode plate N, the positive electrode plate P, and two separators S, respectively, and can wind these up it can. In FIG. 5, the winding part 70 is in a gripping state, and the winding part 71 is in a gripping release state. As shown in FIG. 5, the negative electrode plate N, the positive electrode plate P, and the two separators S are all wound around the winding portion 70 through the gap of the winding portion 71 in the gripped release state.

  Further, a negative electrode defect detection unit 21, a negative electrode gripping unit 31, and a negative electrode cutter 41 are provided in this order on the winding position Y side of the negative electrode unwinding unit 11 in the conveyance path of the negative electrode plate N. The negative electrode defect detection unit 21 is for detecting whether or not there is a defective part in the negative electrode plate N rolled out from the negative electrode unwinding unit 11. The negative electrode gripping portion 31 is for gripping the vicinity of the tip of the negative electrode plate N cut in the width direction by the negative electrode cutter 41. That is, the negative electrode gripping portion 31 takes a state in which the negative electrode plate N is gripped and a state in which the grip is released. Further, the negative electrode gripping portion 31 can move the tip of the gripped negative electrode plate N to the position of the winding portion 71.

  A positive electrode defect detection unit 22, a positive electrode gripping unit 32, and a positive electrode cutter 42 are provided in this order on the winding position Y side of the positive electrode unwinding unit 12 in the conveyance path of the positive electrode plate P. The positive electrode defect detection unit 22 is for detecting whether or not there is a defect in the positive electrode plate P rolled out from the positive electrode unwinding unit 12. The positive electrode gripping portion 32 is for gripping the vicinity of the tip of the positive electrode plate P cut in the width direction by the positive electrode cutter 42. That is, the positive electrode gripping portion 32 takes a state in which the positive electrode plate P is gripped and a state in which the grip is released. Further, the positive electrode gripping portion 32 can move the tip of the gripped positive electrode plate P to the position of the winding portion 71.

  Further, a separator cutter 80 is provided between the winding part 70 and the winding part 71. The separator cutter 80 is for cutting two separators S at a time in the width direction.

  In the state shown in FIG. 5, the winding unit 70 winds the positive electrode plate P, the negative electrode plate N, and the two separators S. For this reason, a wound body is produced at the position of the wound portion 70. After the winding is completed, the manufactured wound body is removed from the winding unit 70 and conveyed to the next process.

  Further, when the winding is completed at the position of the winding part 70, the negative electrode plate N held by the negative electrode holding part 31 and the positive electrode holding part 32 and the gap between the winding parts 71 in the release state are respectively The tip of the positive electrode plate P is inserted. The winding part 71 holds the negative electrode plate N, the positive electrode plate P, and the two separators S by taking a holding state with the tips of the negative electrode plate N and the positive electrode plate P inserted.

  And the winding part 71 which took the holding state is rotationally moved to the direction of arrow Z with the winding part 70 from which the winding body was removed, and the position of the winding parts 70 and 71 is replaced. Thereafter, the winding portion 71 rotates in the direction of the arrow X, whereby the next winding is performed. Thereby, in the electrode winding apparatus 1, a wound body can be continuously produced.

  Here, in the electrode winding apparatus 1 of this embodiment, heating rollers 61 and 62 are provided on the winding path Y side of the separator unwinding portions 13 and 14 in the transport path of the two separators S, respectively. Yes. Further, pre-heating length measuring rollers 51 and 52 and post-heating length measuring rollers 53 and 54 are provided upstream and downstream of the conveying path of the separator S of the heating rollers 61 and 62, respectively.

  The pre-heating length measuring rollers 51 and 52 and the post-heating length measuring rollers 53 and 54 are both pressed against the separator S, and are used for measuring the moving distance of the separator S conveyed along with the winding. . That is, the pre-heating length measuring rollers 51 and 52 are for measuring the moving distance of the separator S before passing through the heating rollers 61 and 62. The post-heating measuring rollers 53 and 54 are for measuring the moving distance of the separator S after passing through the heating rollers 61 and 62.

  The heating rollers 61 and 62 can uniformly heat the separator S in the width direction. Further, each of the heating rollers 61 and 62 can take a contact position in contact with the separator S and a separated position away from the separator S. In FIG. 5, the heating rollers 61 and 62 when in the contact position are indicated by solid lines, and the heating rollers 61 and 62 when in the separation position are indicated by two-dot chain lines.

  At the contact position, the heating rollers 61 and 62 can heat the separator S, which is a porous member, to a temperature at which most of the pores are closed. That is, the heating rollers 61 and 62 can heat the separator S to a temperature equal to or higher than its melting point. Specifically, the heating temperature by the heating rollers 61 and 62 can be 140 ° C. when polyethylene (PE) having a melting point of 125 ° C. is used as the separator S. In addition, the heating temperature of the separator S by the heating rollers 61 and 62 is not high enough to break the separator S.

  On the other hand, in the separated position, the separator S is not heated by the heating rollers 61 and 62. That is, the heating rollers 61 and 62 can heat only a part of the separator S in the transport direction (longitudinal direction) by moving between the contact position and the separation position.

  And the heating rollers 61 and 62 of this form heat only the part which becomes the negative electrode outer peripheral side separator part SCD demonstrated by FIG. Therefore, the heating rollers 61 and 62 are moved to the contact positions when the portions of the separator S that are to be the negative electrode outer peripheral side separator portion SCD pass through the respective positions.

  On the other hand, when the portion of the heating roller 61, 62 on the inner peripheral side of the separator S on the inner peripheral side passes through the position of the negative electrode outer peripheral side separator portion SCD, the heating roller 61, 62 moves to the separated position. Thereby, each of the heating rollers 61 and 62 can heat only the portion of the two separators S that becomes the negative electrode outer peripheral side separator portion SCD.

  Of the separators S unwound from the separator unwinding portions 13 and 14, the position where the portion that becomes the negative electrode outer side separator portion SCD is conveyed can be calculated from the amount of rotation of the winding portion 70. it can. Therefore, the timing at which the portion of the separator S that becomes the negative electrode outer peripheral side separator portion SCD reaches and passes through the positions of the heating rollers 61 and 62 can be calculated from the rotation amount of the winding portion 70.

  Further, the separator S may be slightly extended in the longitudinal direction by being heated by the heating rollers 61 and 62. The amount of elongation of the separator S when it passes through the heating rollers 61 and 62 can be calculated from the detection values of the pre-heating length measuring rollers 51 and 52 and the post-heating length measuring rollers 53 and 54. Therefore, the electrode winding apparatus 1 according to the present embodiment is such that even when the separator S extends when the heating rollers 61 and 62 pass, only the portion of the separator S that becomes the negative electrode outer side separator portion SCD is heated to the heating rollers 61 and 62. Can be accurately heated.

  And the winding body produced with the electrode winding apparatus 1 of this form is shape | molded by the flat shape in the subsequent process, and is set as the electrode body 110. FIG. Further, the electrode body 110 is accommodated in the case main body 131 with the negative electrode terminal 150 and the positive electrode terminal 160 connected thereto. The opening of the case main body 131 in which the electrode body 110 is accommodated is closed when the sealing plate 132 is joined. Further, the battery 100 (FIG. 1) is manufactured by injecting the electrolytic solution 120 into the battery case 130.

  In the battery 100 manufactured in this way, a part of the positive electrode plate P does not react excessively during charging and discharging. In both of the two separators S in the electrode body 110, the pores in the negative electrode outer side separator part SCD are almost closed. For this reason, the amount of the electrolyte 120 held in the negative electrode outer peripheral separator SCD is small, and the reaction during charging / discharging of the outer peripheral surface of the positive electrode outer peripheral negative electrode NC of the negative electrode plate N is suppressed.

  In the above description, the electrode winding apparatus 1 heats the portions that become the negative electrode outer peripheral side separator portion SCD of the two separators S by the heating rollers 61 and 62. However, for example, it is not necessary to heat only the part which becomes one negative electrode outer peripheral side separator part SCD of the two separators S, and to heat the other.

  For example, only a part of the separator S in the longitudinal direction of the negative electrode outer peripheral separator SCD may be heated. Specifically, for example, only one of the SC portion and the SD portion of the separator S shown in FIG. 4 may be heated. Further, for example, only a part of the separator S in the width direction of the negative electrode outer peripheral separator SCD may be heated. In any case, the amount of the electrolyte 120 held in the negative electrode outer separator portion SCD can be reduced, and the reaction during charging / discharging of the outer peripheral surface of the positive electrode outer peripheral negative electrode portion NC of the negative electrode plate N can be suppressed. It is. That is, excessive reaction of the positive electrode plate P can be suppressed.

  Further, as shown in FIG. 2, the flat electrode body 110 of the present embodiment has a flat surface portion and a curved surface portion on the outer peripheral surface. In the battery 100 having such a flat electrode body 110, the excessive reaction of the positive electrode plate P at the time of charging / discharging tends to occur in a portion located on the curved surface portion of the electrode body 110. Therefore, when the electrode body 110 is produced by heating only a part of the negative electrode outer peripheral side separator part SCD of the separator S, the electrode body 110 is wound around the curved surface part of the electrode body 110 of the negative electrode outer peripheral side separator part SCD. It is preferred to heat the part. The excessive reaction of the positive electrode plate P positioned on the curved surface portion of the electrode body 110 is appropriately suppressed by suppressing the reaction at the outer peripheral side of the positive electrode outer peripheral side negative electrode portion NC positioned on the curved surface portion of the electrode body 110. Because it can.

  Further, in the flat electrode body 110 as in the present embodiment, the porous separator separator S wound around the outer peripheral side of the positive electrode outer peripheral side negative electrode part NC of the negative electrode plate N in the curved surface portion of the electrode body 110. It is preferable that the number is one or less from the positive electrode outer peripheral side negative electrode portion NC. In the curved surface portion of the electrode body 110, the number of the porous separators S wound around the outer peripheral side of the negative electrode portion NC on the positive electrode outer periphery side of the negative electrode plate N is set to one or less, thereby It is because an excessive reaction can be suppressed appropriately. Therefore, for example, among the portions wound around the curved surface portion of the electrode body 110 of the negative electrode outer separator portion SCD, the second portion counted from the positive electrode outer peripheral negative electrode portion NC to the outer peripheral side may be heated. Further, in the flat portion of the electrode body 110, the number of porous separators S wound around the outer peripheral side of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is counted from the positive electrode outer peripheral side negative electrode portion NC. The number is preferably 3 or less. In the flat part of the electrode body 110, the number of porous separators S wound around the outer peripheral side of the negative electrode part NC on the positive electrode outer periphery side of the negative electrode plate N is set to 3 or less, so that It is because an excessive reaction can be suppressed appropriately. Therefore, for example, among the portions wound around the flat portion of the electrode body 110 of the negative electrode outer separator portion SCD, the fourth portion counted from the positive electrode outer periphery negative electrode portion NC to the outer periphery may be heated.

  Further, the heating rollers 61 and 62 preferably have a release layer made of fluorine resin or the like on the outermost periphery. It is because it can suppress that the molten material which a part of heated separator S fuse | melts adheres to the surface of the heating rollers 61 and 62. FIG. And by suppressing that the melt of the separator S adheres to the heating rollers 61 and 62, the heating of the separator S by the heating rollers 61 and 62 can be appropriately performed over a long period of time. .

  In addition, for example, when the separator S is a composite material in which a plurality of different materials in the thickness direction are stacked, the material constituting at least one of the plurality of layers has a melting point or higher. What is necessary is just to heat.

  As described above in detail, the electrode body 110 according to the present embodiment is manufactured by forming the wound body wound in a cylindrical shape by the electrode winding apparatus 1 into a flat shape thereafter. The electrode winding apparatus 1 heats the winding body before it is formed into a flat shape, together with the heating rollers 61 and 62 to the melting point or more of the portion that becomes the negative electrode outer side separator portion SCD of the two separators S. While making. The battery 100 is manufactured by housing the produced electrode body 110 together with the electrolytic solution 120 in the battery case 130. In the battery 100, since the pores are closed in the negative electrode outer peripheral side separator portion SCD of the separator S in the electrode body 110, the amount of the electrolyte 120 to be held is reduced. Thereby, the reaction in the outer peripheral surface of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N during charging and discharging of the battery 100 is suppressed. Therefore, the manufacturing method of the secondary battery by which the excessive reaction of the positive electrode at the time of charging / discharging was suppressed is implement | achieved.

[Second form]
Next, the second embodiment will be described. In this embodiment, as the separator, a composite material in which a plurality of different materials are laminated in the thickness direction is used. Specifically, a separator having a surface layer located on the front and back sides and an intermediate layer having a melting point lower than that of the front layer is used between the front and back sides. Then, the separator is heated by the heating roller at a temperature within the range of the melting point of the intermediate layer of the separator and less than the melting point of the surface layer. Except for this, the present embodiment is the same as the first embodiment.

  FIG. 6 shows a cross-sectional view of the separator S used in this embodiment. The separator S has the cross section shown in FIG. 6 in the longitudinal direction and the width direction. As shown in FIG. 6, the separator S of the present embodiment has a three-layer structure having a surface layer S1 positioned on the front and back surfaces and an intermediate layer S2 sandwiched between the front and back surface layers S1.

  In the separator S of this embodiment, both the front and back surface layers S1 are made of a material having a higher melting point than the intermediate layer S2. Specifically, for example, polypropylene (PP) having a melting point of about 180 ° C. can be used for the surface layer S1 of the separator S of the present embodiment. Further, when polypropylene (PP) is used for the surface layer S1, for example, polyethylene (PE) having a melting point of about 125 ° C. can be used for the intermediate layer S2. The combination of the surface layer S1 and the intermediate layer S2 can be a combination other than the combination of polypropylene (PP) and polyethylene (PE).

  And also in this form, the electrode body 110 is produced using the electrode winding apparatus 1 shown in FIG. 5 similarly to the 1st form. That is, the electrode winding apparatus 1 winds the positive electrode plate P, the negative electrode plate N, and the two separators S into a cylindrical shape, thereby producing a wound body before being formed into a flat shape. In this embodiment, the negative electrode plate N, the positive electrode plate P, and the two separators S are wound by the winding portions 70 and 71 of the electrode winding device 1, and the separator S having the three-layer structure shown in FIG. It is performed while unwinding from the outlets 13 and 14.

  Also in this embodiment, the portion that becomes the negative electrode outer side separator portion SCD of the separator S is heated by the heating rollers 61 and 62 of the electrode winding device 1. In this embodiment, the separators S are heated by the heating rollers 61 and 62 at a temperature within the range of the melting point of the intermediate layer S2 and less than the melting point of the surface layer S1. Specifically, in the separator S in which the surface layer S1 is polypropylene (PP) having a melting point of about 180 ° C. and the intermediate layer S2 is polyethylene (PE) having a melting point of about 125 ° C., the heating temperature is 140 ° C. can do.

  Therefore, in this embodiment, the pores of the intermediate layer S2 are almost closed in the portion of the separator S heated by the heating rollers 61 and 62. As a result, the wound body produced in this embodiment is formed into a flat shape to form an electrode body 110. In the battery 100 in which the electrode body 110 is accommodated, the electrolysis held in the negative electrode outer peripheral side separator portion SCD. The amount of the liquid 120 can be reduced. Thereby, also in this form, the reaction at the time of charging / discharging of the outer peripheral surface of the positive electrode outer peripheral side negative electrode part NC of the negative electrode plate N can be suppressed.

  On the other hand, since the heating temperature by the heating rollers 61 and 62 is lower than the melting point of the surface layer S1, the surface layer S1 of the separator S in contact with the heating rollers 61 and 62 is not melted. In other words, in the present embodiment, the melting point of the surface layer S1 of the separator S is higher than the heating temperature of the heating rollers 61 and 62, so that a melt obtained by melting a part of the separator S adheres to the heating rollers 61 and 62. It is definitely suppressed. Thereby, the heating of the separator S by the heating rollers 61 and 62 can be appropriately performed reliably over a long period of time. In the surface layer S1 of the separator S heated by the heating rollers 61 and 62, the pores are hardly closed.

  Also in this embodiment, in the manufactured battery 100, a part of the positive electrode plate P does not react excessively during charging and discharging. In the two separators S in the electrode body 110, the pores in the intermediate layer S2 of the negative electrode outer peripheral separator SCD are almost closed. For this reason, the amount of the electrolyte 120 held in the negative electrode outer peripheral separator SCD is small, and the reaction during charging / discharging of the outer peripheral surface of the positive electrode outer peripheral negative electrode NC of the negative electrode plate N is suppressed.

  Also in this embodiment, for example, only the portion that becomes one negative electrode outer peripheral separator SCD of the two separators S may be heated, and the other may not be heated. For example, it is good also as heating a part in the longitudinal direction or the width direction of the negative electrode outer peripheral side separator part SCD of the separator S. FIG.

  Also in this embodiment, when the electrode body 110 is produced by heating only a part of the negative electrode outer peripheral side separator part SCD of the separator S, the curved surface part of the electrode body 110 of the negative electrode outer peripheral side separator part SCD. It is preferable to heat the portion wound around. The excessive reaction of the positive electrode plate P positioned on the curved surface portion of the electrode body 110 is appropriately suppressed by suppressing the reaction at the outer peripheral side of the positive electrode outer peripheral side negative electrode portion NC positioned on the curved surface portion of the electrode body 110. Because it can.

  Also in the curved surface portion of the electrode body 110 of the present embodiment, the number of the porous separators S wound around the outer peripheral side of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is equal to the positive electrode outer peripheral side negative electrode portion NC. It is preferable that the number is 1 or less. Therefore, for example, among the portions wound around the curved surface portion of the electrode body 110 of the negative electrode outer separator portion SCD, the second portion counted from the positive electrode outer peripheral negative electrode portion NC to the outer peripheral side may be heated. Further, also in the planar portion of the electrode body 110 of the present embodiment, the number of the porous separators S wound around the outer peripheral side of the positive electrode outer peripheral side negative electrode portion NC of the negative electrode plate N is equal to the positive electrode outer peripheral side negative electrode portion NC. It is preferable that the number is 3 or less. Therefore, for example, among the portions wound around the flat portion of the electrode body 110 of the negative electrode outer separator portion SCD, the fourth portion counted from the positive electrode outer periphery negative electrode portion NC to the outer periphery may be heated.

  Also in the present embodiment, it is preferable that the heating rollers 61 and 62 have a release layer made of fluorine resin or the like on the outermost periphery. It is because it can suppress more reliably that the molten material which a part of heated separator S fuse | melts adheres to the surface of the heating rollers 61 and 62. FIG.

  For example, the separator S of this embodiment does not necessarily have to have the surface layer S1 having a higher melting point than the intermediate layer S2 on both the front and back surfaces. That is, the separator S of this embodiment may be any separator having a surface layer S1 having a melting point higher than that of the intermediate layer S2 on at least the surface that comes into contact with the heating rollers 61 and 62. That is, in the electrode winding apparatus 1 (FIG. 5) in which heating is performed by the heating rollers 61 and 62 that are in contact with only one surface of the separator S, the surface layer S1 having a melting point higher than that of the intermediate layer S2 is at least The separator S may be on the surface facing the heating rollers 61 and 62. For this reason, the surface layer S1 may not be provided on the surface of the separator S on the side not in contact with the heating rollers 61 and 62. This is because the adhesion of the separator S to the heating rollers 61 and 62 can be suppressed.

  As described above in detail, in this embodiment, the separator S having the surface layer S1 and the intermediate layer S2 is used. The surface layer S1 is made of a material having a higher melting point than the intermediate layer S2. The electrode winding apparatus 1 is configured such that the winding body before being formed into a flat shape and the portion that becomes the negative electrode outer side separator portion SCD of the two separators S are heated by the heating rollers 61 and 62 to the intermediate layer S2. It is produced while heating at a temperature within the range of the melting point of the surface layer S1 and less than the melting point of the surface layer S1. The battery 100 is manufactured by housing the produced electrode body 110 together with the electrolytic solution 120 in the battery case 130. In the battery 100, since the pores of the intermediate layer S2 are closed at the negative electrode outer peripheral side separator portion SCD of the separator S in the electrode body 110, the amount of the electrolyte 120 to be held is reduced. Thereby, the manufacturing method of the secondary battery by which the excessive reaction of the positive electrode at the time of charging / discharging was suppressed is implement | achieved.

  Note that this embodiment is merely an example, and does not limit the present invention. Accordingly, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the present invention is not limited to the battery 100 described in the above embodiment, and can be applied to any method for manufacturing a secondary battery having a wound electrode body. That is, the present invention can be applied not only to the flat electrode body 110 but also to a method for manufacturing a lithium ion secondary battery having a cylindrical wound electrode body. Further, the present invention is not limited to the lithium ion secondary battery, and can be applied to other methods for manufacturing a chargeable / dischargeable secondary battery such as a nickel hydride secondary battery.

DESCRIPTION OF SYMBOLS 1 Electrode winding device 11 Negative electrode unwinding part 12 Positive electrode unwinding part 13, 14 Separator unwinding part 61, 62 Heating roller 70, 71 Winding part Y Winding position 100 Battery 110 Electrode body 120 Electrolytic solution 130 Battery case N Negative electrode Plate P Positive electrode plate S Separator

Claims (1)

The battery case has an electrode body formed by winding a positive electrode plate, a negative electrode plate, and a separator, and an electrolyte solution.
The electrode body has a flat portion having a flat outer peripheral surface and a curved surface portion having a curved outer peripheral surface;
For the electrode body, the negative electrode plate has a positive electrode outer peripheral side negative electrode portion wound around a position on the outer peripheral side with respect to a positive electrode outermost peripheral portion located on the outermost outer periphery of the positive electrode plate, and the separator, In the method of manufacturing a secondary battery, which has a negative electrode outer peripheral side separator portion wound at a position on the outer peripheral side of the positive electrode outer peripheral side negative electrode portion,
Winding the positive electrode plate, the negative electrode plate, and the separator from the respective unwinding positions, and winding the positive electrode plate and the negative electrode plate at the winding position with the separator interposed therebetween. An electrode body manufacturing step of manufacturing the electrode body by,
An assembly step of accommodating the electrode body in the battery case and injecting the electrolyte into the battery case;
In the electrode body manufacturing step, at least a portion of the separator that becomes the negative electrode outer side separator portion and a portion that is located on the curved surface portion between the separator unwinding position and the winding position. A method for producing a secondary battery, wherein a part of the battery is heated to a melting point or higher.

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