JP6194707B2 - Power storage device and method for manufacturing power storage device - Google Patents

Description

  The present invention relates to a power storage device in which a thickness adjusting member is disposed between an end face of an electrode assembly in a stacking direction and a wall portion of a case, and a method for manufacturing the power storage device.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. The secondary battery includes, for example, an electrode assembly in which a rectangular positive electrode having an active material layer formed on both sides and a negative electrode are stacked with a separator interposed therebetween.

  Among secondary batteries, when manufacturing a square secondary battery, a positive electrode, a separator, and a negative electrode are stacked to form an electrode assembly, and then the electrode assembly is in a state in which a load is applied in the stacking direction. The length in the stacking direction in the restrained state is measured. Then, it is determined whether or not the length in the stacking direction is within a predetermined value range. If the length of the electrode assembly in the stacking direction is not within a predetermined value range, for example, in the case, the end surface in the stacking direction of the electrode assembly and the inner surface of the wall of the case facing the end surface The gap between them becomes too large, and the electrode assembly moves in the stacking direction within the case, which is not preferable.

  For this reason, in a square secondary battery, a structure in which a gap is eliminated by inserting a thickness adjusting member into the electrode assembly in a gap between the electrode assembly and the case is proposed (for example, Patent Document 1). ).

JP 2008-108457 A

  By the way, in the initial stage of the manufacturing process, the positive electrode or the negative electrode has a long band shape, and is stored or transported in the state of a roll wound around the core. For this reason, the positive electrode or the negative electrode has a warp in an unconstrained state. In the case of using the thickness adjusting member, in order to overlap the thickness adjusting member, the state in which a load is applied to the electrode assembly must be once released. For this reason, when releasing the state in which the load is applied to the electrode assembly, or when stacking the thickness adjusting member after the release, the positive electrode, the separator, and the negative electrode are caused by the warp described above, and the active material layer There is a risk that a stacking shift that shifts in a direction along the surface of the film will occur.

  An object of the present invention is to provide a power storage device and a method for manufacturing the power storage device that can suppress stacking deviation of the electrode assembly while using the thickness adjusting member.

The electric storage device for solving the problem, one electrode assembly and a rectangular sheet-like positive electrode and a rectangular sheet-shaped negative electrode is constituted by Rukoto are stacked in a state of being interposed between the separator there is accommodated in a case, a power storage device thickness adjusting member is disposed between the wall of the casing facing the end face and end face located at least one end of the stacking direction of the electrode assembly, wherein a plurality of the cathode electrodes constituting one electrode assembly, the negative electrode, and has a first holding tape for holding together the separator, the electrode assembly held by said first holding tape And a second holding tape for holding the thickness adjusting member integrally.

  According to this, in the electrode assembly, the stacking deviation is suppressed by the first holding tape. In addition, the electrode assembly and the thickness adjusting member are prevented from being misaligned by the second holding tape. Therefore, even when the thickness adjusting member is stacked on the electrode assembly, the electrode assembly is independently held by the first holding tape, so that the stacking deviation of the electrode assembly when the thickness adjusting member is stacked can be suppressed. .

The power storage device is a secondary battery.
A method for manufacturing a power storage device, a rectangular sheet-like positive electrode and a rectangular sheet-shaped negative electrode and is in one of the electrode assemblies cases comprised Rukoto are stacked in a state of being interposed between the separator to be accommodated, a method of manufacturing a power storage device thickness adjusting member is disposed between the wall of the casing facing the end face and end face located at least one end of the stacking direction of the electrode assembly, a plurality The positive electrode, the separator, and the negative electrode are stacked to form the one electrode assembly, and the electrode assembly is held by the first holding tape in a state where a load is applied in the stacking direction of the electrode assembly. after at least one lap of the thickness adjusting member to said end face, and wherein the thickness adjusting member and while applying the load to the electrode assembly, wherein the thickness adjusting member and the electrode assembly of the electrode assembly And summarized in that held in the second holding tape.

  According to this, at the time of manufacturing the power storage device, after the positive electrode, the separator, and the negative electrode are stacked to form the electrode assembly, the electrode assembly is restrained with a load applied in the stacking direction. The electrode assembly is held by the first holding tape in this constrained state, and the length in the stacking direction is measured in a state in which stacking shift is suppressed. If the length in the stacking direction is not within the range of the predetermined value, the load applied to the electrode assembly is released, and the thickness adjusting member is stacked on the electrode assembly. When the load is released and when the thickness adjusting member is stacked, the stacking displacement of the electrode assembly can be suppressed by the first holding tape. Then, after the thickness adjusting members are stacked, the electrode assembly and the thickness adjusting member are constrained in the stacking direction again with a load applied in the stacking direction. In this constrained state, the electrode assembly and the thickness adjusting member are integrally held by the second holding tape to suppress stacking deviation. For this reason, when the load is released, the stacking deviation of the electrode assembly can be suppressed by the first holding tape, and the stacking shift of the thickness adjusting member can also be suppressed by the second holding tape.

Further, regarding the method for manufacturing the power storage device, the holding force of the second holding tape and the holding force of the first holding tape were made different.
According to this, by dividing into the first holding tape and the second holding tape, the electrode assembly and the thickness adjusting member can be held with a holding force suitable for holding each.

  According to the present invention, stacking deviation of the electrode assembly can be suppressed while using the thickness adjusting member.

The disassembled perspective view which shows a secondary battery. The perspective view which shows the external appearance of a secondary battery. The disassembled perspective view which shows an electrode assembly and a thickness adjustment member. The perspective view which shows the state which integrated the electrode assembly and the thickness adjustment member. FIG. 5 is a sectional view taken along line 5-5 in FIG. 2 showing the inside of the secondary battery. (A) is a side view which shows the state which applied the load to the electrode assembly, (b) is a side view which shows the state which applied the load to the electrode assembly and was hold | maintained with the 1st holding tape. (A) is a side view which shows the state which accumulated the thickness adjustment member on the electrode assembly, (b) is a side view which shows the state which hold | maintained the thickness adjustment member with the 2nd holding tape.

Hereinafter, an embodiment in which a power storage device and a manufacturing method thereof are embodied in a secondary battery and a manufacturing method of a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1, 2, and 5, the secondary battery 10 is a lithium ion secondary battery, and includes a metal case 11 that forms the outline of the secondary battery 10. The case 11 includes a bottomed rectangular parallelepiped container 12 having an opening 12a on one surface and a lid 13 that closes the opening 12a. The container 12 has a rectangular bottom plate 12b, a short side wall 12c erected from a pair of opposed short side edges of the bottom plate 12b, and a long side wall 12d erected from a pair of opposed long side edges of the bottom plate 12b. Is provided. The case 11 contains an electrode assembly 14 and an electrolytic solution (not shown) as an electrolyte. The electrode assembly 14 has a rectangular parallelepiped shape as a whole, corresponding to the internal space of the container 12 having a rectangular parallelepiped shape.

  As shown in FIG. 3, the electrode assembly 14 is made of a rectangular sheet-like positive electrode 21 and a rectangular sheet-like negative electrode 22, and is made of a resin and is porous so that ions (lithium ions) related to electric conduction can pass therethrough. And a separator 23 formed of a material film. The positive electrode 21 includes a rectangular positive electrode metal foil (aluminum foil in this embodiment) 21a and a rectangular positive electrode active material layer 21b provided on both surfaces (surfaces) of the positive electrode metal foil 21a. . Around the positive electrode active material layer 21b, an uncoated portion having no active material is formed on the surface of the positive electrode metal foil 21a (in the present embodiment, the number of uncoated portions is small, and is not shown). . A positive electrode current collecting tab 41 is provided on a part of the first side (upper side) 21c of the positive electrode 21 so as to project a part of the positive electrode metal foil 21a. In the positive electrode 21, the opposite side of the first side 21c provided with the positive current collecting tab 41 is the second side 21e, and a pair of sides connecting the first side 21c and the second side 21e is the third side. 21f.

  The negative electrode 22 has a rectangular negative electrode metal foil (copper foil in this embodiment) 22a and a rectangular negative electrode active material layer 22b provided on both surfaces (surfaces) of the negative electrode metal foil 22a. . Around the negative electrode active material layer 22b, an uncoated portion having no active material is formed on the surface of the negative electrode metal foil 22a (in the present embodiment, the number of uncoated portions is small, and is not shown). . A negative electrode current collecting tab 42 is provided on a part of the first side (upper side) 22c of the negative electrode 22 so as to project a part of the negative electrode metal foil 22a.

  In the negative electrode 22, the opposite side of the first side (upper side) 22c provided with the negative current collecting tab 42 is defined as a second side 22e, and a pair of sides connecting the first side 22c and the second side 22e is defined as a first side. 3 side 22f. In the separator 23, a side disposed on the positive electrode current collecting tab 41 and negative electrode current collecting tab 42 side is a first side 23c, and a side opposite to the first side 23c is a second side 23e. In the separator 23, a pair of sides connecting the first side 23c and the second side 23e are defined as a third side 23f.

  The negative electrode metal foil 22 a and the positive electrode metal foil 21 a are formed in the same size as the separator 23 except for the tabs 41 and 42. However, the lengths of the two adjacent sides of the negative electrode active material layer 22b (the length in the longitudinal direction and the length in the short direction) are the lengths of the two adjacent sides of the positive electrode active material layer 21b. It is set longer than (the length in the longitudinal direction and the length in the short direction). That is, the negative electrode active material layer 22b is set to a size that can cover the surface of the positive electrode active material layer 21b. In addition, since an uncoated portion is formed around the positive electrode active material layer 21b and the negative electrode active material layer 22b, the separator 23 covers both the surface of the negative electrode active material layer 22b and the surface of the positive electrode active material layer 21b. It is possible to cover.

  As shown in FIGS. 1 and 4, the positive electrode 21, the negative electrode 22, and the separator 23 are arranged such that the positive electrode current collecting tabs 41 are arranged in a line along the stacking direction and do not overlap the positive electrode current collecting tabs 41. The negative electrode current collecting tabs 42 are stacked at the position so as to be arranged in a line along the stacking direction. The electrode assembly 14 includes a tab-side end surface 36 formed by gathering the first sides 21c, 22c, and 23c. In the tab-side end surface 36, the positive current collecting tab 41 and the negative current collecting tabs 36 are provided. The electric tab 42 is bent in a state of being collected (bundled) within a range from one end to the other end in the stacking direction of the electrode assembly 14. Each positive current collecting tab 41 is electrically connected by welding a portion where each positive current collecting tab 41 overlaps, and a positive electrode conductive member 61 is connected to the positive current collecting tab 41. A positive electrode terminal 51 for taking out electricity from the electrode assembly 14 is connected to the positive electrode conductive member 61.

  Similarly, the negative electrode current collecting tabs 42 are electrically connected by welding the portions where the negative electrode current collecting tabs 42 are overlapped, and the negative electrode conductive member 62 is connected to the negative electrode current collecting tabs 42. A negative electrode terminal 52 for taking out electricity from the electrode assembly 14 is connected to the negative electrode conductive member 62. The positive terminal 51 and the negative terminal 52 penetrate the lid 13 and protrude out of the case 11, and the positive terminal 51 and the negative terminal 52 are insulated from the lid 13 by the insulating ring 13a.

  The length L in the stacking direction of the electrode assembly 14 is slightly smaller than the inner dimension of the case 11. This is because when a predetermined number of positive electrodes 21, negative electrodes 22, and separators 23 are stacked, the electrode assembly 14 can be accommodated in the case 11 even if the actual thickness takes the maximum manufacturing tolerance. , Because each thickness is set.

  The electrode assembly 14 includes a bottom surface 37 in which the second sides 21e, 22e, and 23e are gathered together, and the bottom surface 37 is located on the opposite side of the tab-side end surface 36 with the electrode assembly 14 interposed therebetween. . Furthermore, the electrode assembly 14 includes a pair of side surfaces 38 in which the third sides 21f, 22f, and 23f are gathered together. The pair of side surfaces 38 are two surfaces excluding both end surfaces 44 in the stacking direction among the surfaces connected to the bottom surface 37 in the electrode assembly 14.

  As shown in FIG. 1, in the electrode assembly 14, a large number of positive electrodes 21, negative electrodes 22, and separators 23 are fixed to each other by first holding tapes 45 and 47. Two first holding tapes 45 are attached to the bottom surface 37 side of the electrode assembly 14 from the bottom surface 37 side. Each first holding tape 45 has a band shape and is attached in a U-shaped cross section. The first holding tape 45 is attached to both end surfaces 44 of the electrode assembly 14 at both ends in the longitudinal direction and covers a part of the bottom surface 37. In the electrode assembly 14, when the width direction is a direction orthogonal to the stacking direction along the bottom surface 37, the two first holding tapes 45 are separated in the width direction of the electrode assembly 14.

  Another first holding tape 47 is attached to each side surface 38 that is both sides in the width direction of the electrode assembly 14 so as to cover each side surface 38. Each first holding tape 47 has a strip shape and is attached in a U-shaped cross section. The first holding tape 47 is attached to both end surfaces 44 of the electrode assembly 14 at both ends in the longitudinal direction and covers a part of the side surface 38.

  Then, the first holding tapes 45 and 47 suppress the movement of the positive electrode 21, the negative electrode 22, and the separator 23 in all directions along the stacking direction, the width direction, and the end surface 44 (lamination misalignment). Are held together. Therefore, in the electrode assembly 14, the positive electrode active material layer 21 b and the negative electrode active material layer 22 b face each other with the separator 23 interposed therebetween.

  The first holding tapes 45 and 47 are made of a material made of polypropylene (PP) or polyfinylene sulfide (PPS) provided with an adhesive layer on one surface, and are made of a material that is not easily torn.

  As shown in FIG. 5, a thickness adjusting member 50 is interposed between one end face 44 of the electrode assembly 14 and one long side wall 12d. The thickness adjusting member 50 is a resin film having a predetermined thickness and corresponds to the length L in the stacking direction of the electrode assembly 14, and one or more sheets are stacked. In FIG. 5, one thickness adjusting member 50 is described.

  As shown in FIG. 4, the thickness adjusting member 50 is held integrally with the electrode assembly 14 by the second holding tape 48. The second holding tape 48 is affixed to the electrode assembly 14 and the thickness adjusting member 50 from the tab side end face 36 side and the bottom face 37 side, which are opposing faces of the electrode assembly 14. The second holding tape 48 has a band shape and is attached in a U-shaped cross section. The second holding tape 48 has one end in the longitudinal direction attached to the other end face 44 of the electrode assembly 14 and the other end in the longitudinal direction attached to the thickness adjusting member 50. In addition, the 2nd holding tape 48 is provided with an adhesive layer on one surface of a base material made of polypropylene (PP) or polyfinylene sulfide (PPS), and is made of a material that is not easily torn.

  By using the thickness adjusting member 50, the length in the stacking direction of the electrode assembly 14 and the thickness adjusting member 50 is adjusted within a predetermined range. In the case 11, the electrode assembly 14 in which the thickness adjusting member 50 is integrated is restricted in the stacking direction and restricted in the stacking direction by the thickness adjusting member 50.

Next, the manufacturing method of the secondary battery 10 will be described together with the operation.
As shown in FIG. 6A, the positive electrode 21, the separator 23, and the negative electrode 22 are alternately stacked on the mounting table 70. When the predetermined number of positive electrodes 21, separators 23, and negative electrodes 22 are stacked, a load K is applied to one end face 44 of the electrode assembly 14 in the stacking direction.

  Next, as shown in FIG. 6B, with the load K applied to the electrode assembly 14, first holding tapes 45 and 47 are affixed to both end faces 44 of the electrode assembly 14, and the first The electrode assembly 14 is held by the holding tapes 45 and 47 so that the stacking deviation is suppressed. At this time, in order to hold the electrode assembly 14 in the stacking direction from the both end surfaces 44 side, the first holding tapes 45 and 47 are applied while applying a stronger tension than the second holding tape 48 described later. The

  Next, the length L in the stacking direction of the electrode assembly 14 to which the load K is applied and constrained in the stacking direction is measured. Then, based on the measured length L of the electrode assembly 14 in the stacking direction, the number of films used as the thickness adjusting member 50 is determined.

  Next, the thickness adjusting member 50 is overlaid on the electrode assembly 14. At this time, the first holding tapes 45 and 47 are partially attached to the both end surfaces 44 of the electrode assembly 14, whereas the thickness adjusting member 50 is attached to both end surfaces 44 of the electrode assembly 14. It contacts the entire surface except the current collecting tabs 41 and 42. Therefore, as shown in FIG. 7A, the state where the load K is applied to the electrode assembly 14 is released, and then the thickness adjusting member 50 is placed on one end face 44 of the electrode assembly 14. At this time, the thickness adjusting member 50 is overlaid on the first holding tapes 45 and 47.

  Thereafter, as shown in FIG. 7B, a load K in the stacking direction is applied to the thickness adjusting member 50, and the load K is applied to the thickness adjusting member 50 and the other end surface 44 of the electrode assembly 14. A second holding tape 48 is attached, and the thickness adjusting member 50 is fixed to the electrode assembly 14. Then, the electrode assembly 14 and the thickness adjusting member 50 are integrated by the second holding tape 48, and the length in the stacking direction of the electrode assembly 14 and the thickness adjusting member 50 is within a predetermined value range. The length is confirmed.

Thereafter, the electrode assembly 14 in which the thickness adjusting member 50 is integrated is inserted into the container 12 through the opening 12a, and the opening 12a is closed with the lid 13, whereby the secondary battery 10 is manufactured.
According to the above embodiment, the following effects can be obtained.

  (1) The electrode assembly 14 was laminated, and the electrode assembly 14 was held by the first holding tapes 45 and 47 with the load K applied. For this reason, in order to stack the thickness adjusting member 50 on the electrode assembly 14, when the load K applied to the electrode assembly 14 is released or when the thickness adjusting member 50 is stacked, the first holding tape 45, 47 is used. Lamination displacement of the electrode assembly 14 can be suppressed.

  (2) The electrode assembly 14 and the thickness adjusting member 50 are overlapped, and the electrode assembly 14 and the thickness adjusting member 50 are held by the second holding tape 48 in a state where the load K is applied. For this reason, after the thickness adjusting member 50 is overlapped and the load K is applied, the stacking deviation of the thickness adjusting member 50 can be suppressed by the second holding tape 48 when the load is released.

  Therefore, when the thickness adjusting member 50 is used, the stacking deviation of the electrode assembly 14 can be suppressed. Further, since the thickness adjusting member 50 is used, no gap is formed between both end surfaces 44 in the stacking direction of the electrode assembly 14 and the opposing long side wall 12d, and movement in the stacking direction of the electrode assembly 14 is suppressed. In addition, the active material layers 21b and 22b can be opposed to each other with the separator 23 interposed therebetween.

  (3) The thickness adjusting member 50 is fixed to the electrode assembly 14 by the second holding tape 48 provided separately from the first holding tapes 45 and 47 that hold the electrode assembly 14. For this reason, the holding force (tension) can be made different between the first holding tapes 45 and 47 and the second holding tape 48. Accordingly, the first holding tapes 45 and 47 can increase the holding force in order to suppress the stacking deviation in the electrode assembly 14. On the other hand, in the thickness adjusting member 50 made of a resin film, the second holding tape 48 can be stuck with a weak holding force in order to suppress the generation of wrinkles and the bending caused by the sticking.

  (4) The electrode assembly 14 is held by the first holding tapes 45 and 47, and the thickness adjusting member 50 is held integrally by the electrode assembly 14 by the second holding tape 48. For this reason, the electrode assembly 14 and the thickness adjusting member 50 can be integrated and inserted into the container 12, and the insertion operation is easily performed as compared with the case where the electrode assembly 14 and the thickness adjusting member 50 are separately inserted into the container 12. be able to.

In addition, you may change the said embodiment as follows.
The position where the first holding tapes 45 and 47 are affixed may be changed as appropriate.
The position where the second holding tape 48 is affixed may be changed as appropriate.

  ○ The thickness adjusting member 50 may use films having different thicknesses. In the embodiment, the thickness is adjusted by using one to a plurality of films having a constant thickness. For example, a plurality of films having different thicknesses are used, and the gap is set according to the length L in the stacking direction of the electrode assembly 14. An appropriate film that fits may be selected.

The thickness adjusting member 50 may be made of metal instead of resin, may be a single metal plate, or may be configured by laminating a plurality of metal sheets.
In the embodiment, in the secondary battery 10, the thickness adjusting member 50 is disposed between one end surface 44 in the stacking direction of the electrode assembly 14 and the one long side wall 12 d, but is not limited thereto. For example, the thickness adjusting member 50 may be disposed between both end surfaces 44 of the electrode assembly 14 in the stacking direction and the long side walls 12d. In this case, both thickness adjusting members 50 are integrated with the electrode assembly 14 by the second holding tape 48.

The number of positive electrodes 21 and negative electrodes 22 constituting the electrode assembly 14 may be changed as appropriate.
In the embodiment, the positive electrode 21 has the positive electrode active material layer 21b on both sides of the positive electrode metal foil 21a, but may have the positive electrode active material layer 21b only on one side of the positive electrode metal foil 21a. . Similarly, the negative electrode 22 has the negative electrode active material layer 22b on both surfaces of the negative electrode metal foil 22a, but may have the negative electrode active material layer 22b only on one surface of the negative electrode metal foil 22a.

O You may actualize as a nickel-hydrogen secondary battery as an electrical storage apparatus, or an electric double layer capacitor.
Next, a technical idea that can be grasped from the above embodiment and another example will be described.

  (A) The power storage device according to claim 1 or 2, wherein the thickness adjusting member is made of a resin film.

  K: Load, 10: Secondary battery as power storage device, 11: Case, 12d: Long side wall as wall, 14: Electrode assembly, 21: Positive electrode, 22: Negative electrode, 23: Separator, 44: End face 45, 47 ... first holding tape, 48 ... second holding tape, 50 ... thickness adjusting member.

Claims (4)

One electrode assembly and a rectangular sheet-like positive electrode and a rectangular sheet-shaped negative electrode is constituted by Rukoto are stacked in a state of being interposed between a separator is housed in the case, of the electrode assembly A power storage device in which a thickness adjusting member is disposed between an end face located at least one end in the stacking direction and a wall portion of the case facing the end face,
A plurality of the positive electrodes, the negative electrodes, and the first holding tape that integrally hold the separator that constitute the one electrode assembly ;
A power storage device comprising: a second holding tape that holds the electrode assembly held by the first holding tape and the thickness adjusting member integrally.   The power storage device according to claim 1, wherein the power storage device is a secondary battery. One electrode assembly and a rectangular sheet-like positive electrode and a rectangular sheet-shaped negative electrode is constituted by Rukoto are stacked in a state of being interposed between a separator is housed in the case, of the electrode assembly A method of manufacturing a power storage device in which a thickness adjusting member is disposed between an end face located at least one end in a stacking direction and a wall portion of the case facing the end face,
A plurality of the positive electrode, the separator, and the negative electrode are stacked to form the one electrode assembly, and the electrode assembly is covered with a first holding tape in a state where a load is applied in the stacking direction of the electrode assembly. after holding,
The electrode assembly and the thickness adjusting member are connected to each other in a state where the thickness adjusting member is overlaid on at least one end face of the electrode assembly and the load is applied to the thickness adjusting member and the electrode assembly. A method for manufacturing a power storage device, characterized by being held by a holding tape.   The method for manufacturing a power storage device according to claim 3, wherein the holding force of the second holding tape is different from the holding force of the first holding tape.