JP6163847B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery having a structure in which positive electrodes and negative electrodes are alternately stacked with a separator interposed therebetween.

  As the battery, there is a non-aqueous electrolyte secondary battery, for example, a lithium ion secondary battery. This secondary battery has a core (internal structure) in which a positive electrode and a negative electrode are laminated in multiple layers with a separator interposed therebetween. The separator has a function of preventing the electrodes from contacting each other and moving lithium ions and an electrolytic solution. In order to satisfy these functions, the separator is made of a polymer resin such as a porous sheet, and softens and melts depending on temperature conditions. A secondary battery having such a separator uses this property of the separator to suppress abnormal charging and discharging accompanied by a temperature rise.

  When the temperature of the secondary battery rises due to overcharge of the secondary battery or a short circuit between the electrodes, this separator moderately softens and melts and stops moving lithium ions between the positive and negative electrodes. Also, it has the function of making subsequent charge / discharge impossible. This function of the separator is called “shutdown”.

  Moreover, there is a limit to this shutdown function, and when the temperature of the secondary battery further rises beyond the temperature at which the shutdown function is exhibited, the separator may be softened and melted more than necessary and may shrink. In particular, when abnormal heat generation occurs, heat accumulates inside and the temperature rises first from the central portion. The separator is made to have a slightly larger outer dimension than the plate-like electrode, but when the temperature rises in the central part of the secondary battery, the shrinkage proceeds from the central part. As a result, the electrodes are partially exposed and contact and short circuit with each other. The situation where the secondary battery is in this state is called “meltdown”.

  In order to prevent meltdown while making use of the shutdown function, it has been studied to manufacture a separator having a multilayer structure in which a plurality of materials having different melting points are laminated. For example, as the simplest technique, Patent Document 1 discloses a separator that uses a non-woven fabric using a high melting point material such as polyimide and a microporous film using a low melting point material such as polypropylene as two layers.

  This Patent Document 1 shows a secondary battery in which a separator is formed in a bellows fold and an electrode sheet is inserted from each folded side. This secondary battery has an electrode active material layer on the surface of the electrode sheet. If the electrode active material layer is peeled off due to various stresses during the manufacturing process, the separator may be damaged and cause a short circuit. The area where the electrode active material layer is not applied is formed in the bent portion where is folded.

  The stacked battery described in Patent Document 2 includes a stacked battery body in which a plurality of positive electrodes and negative electrodes are alternately stacked via separators. At this time, the separators are joined to each other at least at a part of the peripheral edge for each pair adjacent in the stacking direction, and are formed in a bag shape. A positive electrode is inserted into the bag-shaped separator. A bag-shaped separator in which a positive electrode is placed and a negative electrode are laminated to form a laminated electrode body. As for the joint portions of the pair of separators joined together, the separator located in the central region in the stacking direction has a smaller joining ratio than the separators positioned at both ends in the stacking direction.

JP 2012-1114075 A JP 2012-69378 A

  However, as in Patent Document 1, a separator having a multilayer structure made of different materials in order to suppress the shrinkage of the separator requires a manufacturing cost of the separator. And it is not easy to heat-weld the separator of a laminated structure.

  Further, hydrogen gas may be generated in a situation where the secondary battery generates abnormal heat. If the generated gas accumulates too much inside the secondary battery, the case of the secondary battery may be deformed or damaged by the internal pressure. Therefore, a safety valve that is opened when the internal pressure becomes higher than the set pressure is provided in the case. However, since such a gas cannot pass through the separator, if it accumulates inside a portion that is accordion-folded or continuously welded as in Patent Document 1, it is difficult for the gas to be discharged out of the separator. This causes deformation of the secondary battery case.

  In the case of the stacked battery of Patent Document 2, each pair of separators adjacent to each other in the stacking direction is bonded in a bag shape, and the bonding portion is obtained by changing the ratio of the bonded portion between the lower layer portion and the upper layer portion in the stacking direction. Yes. Patent Document 2 considers the diffusibility (around the liquid) of the electrolyte in the battery, that is, the electrolyte permeates homogeneously to the center of the electrode plate. However, it does not take into account that gas accumulates.

  Accordingly, the present invention provides a secondary battery that has a structure that prevents the separator from contracting when abnormal heat is generated, and prevents gas from being accumulated between the separators.

A secondary battery according to an embodiment of the present invention includes a core formed by alternately laminating a positive electrode and a negative electrode with a separator having a first side and a second side located on the opposite side in between. Prepare. The separator has a joint region that is intermittently joined in each layer of the core so that the adhesive portion and the non-adhesive portion are alternately formed with respect to at least one separator adjacent in the stacking direction. This junction region includes a first junction region in which the first sides are intermittently joined and a second junction region in which the second sides are intermittently joined. The positive electrode and the negative electrode have a positive electrode current collector terminal and a negative electrode current collector terminal that intersect the first side or the second side and extend outward from the outer periphery of the separator.

  At this time, the separator is bonded at the first bonding region to the one-side separator adjacent on one side in the stacking direction, and bonded at the second bonding region to the opposite-side separator adjacent on the opposite side in the stacking direction. Is done.

  In addition, when the secondary battery further includes a container that stores the core and a safety valve that is provided on the outer peripheral wall of the container and that is opened when the internal pressure exceeds the set value, the secondary battery is provided in a range that faces the safety valve. The adhesive part is made smaller in the direction along the outer periphery of the positive electrode and the negative electrode than the other adhesive parts, and the non-adhesive part provided in the range facing the safety valve is arranged on the outer periphery of the positive electrode and the negative electrode more than the other non-adhesive parts. Increase along the direction. In the case of a secondary battery having a width in a direction away from the outer periphery of the positive electrode and the negative electrode, the bonding length on the inner peripheral side of the separator in the direction along the outer periphery of the positive electrode and the negative electrode is set to the outer peripheral side of the separator. The welding length is made smaller. In addition, the welding length on the outer peripheral side of the separator in the bonded portion is made larger than the non-bonded length on the outer peripheral side of the separator in the non-bonded portion.

The positive electrode current collector terminal and the negative electrode current collector terminal each have a coupling portion provided with a plurality of holes penetrating in the laminating direction at least in a range crossing the bonding region, and the separator is in relation to the separator adjacent in the laminating direction, It joins through the coupling | bond part of a positive electrode current collection terminal and a negative electrode current collection terminal.

According to the secondary battery of one embodiment of the present invention, the separator inserted between the positive electrode and the negative electrode has a first side and a second side located on the opposite side, and is arranged in the stacking direction. It has a joint region that is intermittently joined in each layer of the core so that an adhesive portion and a non-adhesive portion are alternately formed with respect to at least one separator adjacent to each other, and the first sides are in the joint region. look including a second junction region each other first junction region and a second side that are joined are joined, positive and negative electrodes, the outer periphery of the separator intersects the first side or the second side In addition, since the positive electrode current collector terminal and the negative electrode current collector terminal that extend outward are included , the separator is prevented from contracting, and the gas generated on the surface of the electrode is easily discharged from the non-adhesive portion to the outside of the core.

The disassembled perspective view of the secondary battery of the 1st Embodiment of this invention. Sectional drawing which cut the core of FIG. 1 in the lamination direction. The figure which shows the joining area | region of a separator in the cross section which follows the F3-F3 line | wire in FIG. Sectional drawing which cut the core of the secondary battery of the 2nd Embodiment of this invention in the lamination direction. The figure which shows the joining area | region of a separator in the cross section which follows the F5-F5 line | wire in FIG. The figure which shows the junction area | region of the separator at the time of seeing the core of the secondary battery of the 3rd Embodiment of this invention in the lamination direction. The figure which shows the junction area | region of the separator at the time of seeing the core of the secondary battery of the 4th Embodiment of this invention in the lamination direction. The figure which shows the junction area | region of the separator at the time of seeing the core of the secondary battery of the 5th Embodiment of this invention in the lamination direction. Sectional drawing which cut the core of the secondary battery of the 6th Embodiment of this invention in the lamination direction. The figure which shows the joining area | region of a separator in the cross section which follows the F10-F10 line | wire in FIG. The figure which expanded the coupling | bond part of FIG.

  A secondary battery 1 according to a first embodiment of the present invention will be described with reference to FIGS. A secondary battery 1 shown in FIG. 1 includes a rectangular container 2 having both ends opened, an electrode lid 3 that seals the opening, and a core (stacked body) 10 that is stored in the container 2. ing. The container may be a metal can or a bag formed of a laminate film. As shown in FIG. 1, the container 2 has a safety valve 21 on the outer peripheral wall. The safety valve 21 is opened when a preset internal pressure is exceeded, and the container 2 is prevented from being damaged.

  The core 10 is configured by alternately laminating positive electrodes 12 and negative electrodes 13 with a separator 11 interposed therebetween. In FIG. 1, the positive electrode 12, the negative electrode 13, and the separator 11 are shown in a developed state. The core 10 shown in FIG. 1 has a configuration in which five positive electrodes 12 and five negative electrodes 13 are stacked, but the number of stacked electrodes is not limited to this. As shown in FIGS. 2 and 3, the positive electrode 12 is formed so that the outer dimensions are slightly smaller than the negative electrode 13. The separator 11 is formed larger than the outer dimensions of the negative electrode 13. The separator 11 has a first side 111 and a second side 112 located opposite to the first side 111.

  As shown in FIG. 2, the positive electrode 12 is formed with a positive electrode material 122 serving as a positive electrode active material on both sides of a positive electrode current collecting terminal 121 made of, for example, square foil-shaped aluminum. As shown in FIG. 2, the negative electrode 13 is formed with a negative electrode material 132 serving as a negative electrode active material on both sides of a negative electrode current collecting terminal 131 made of copper having a rectangular foil shape. Further, the positive electrode 12 has a positive electrode lead portion 123 in which a part of the positive electrode current collecting terminal 121 extends outside the range where the positive electrode material 122 is formed. The negative electrode 13 has a negative electrode lead part 133 in which a part of the negative electrode current collecting terminal 131 extends outside the range where the negative electrode material 132 is formed. The positive electrode lead portion 123 and the negative electrode lead portion 133 extend outward from the outer periphery of the separator 11.

  In the case of the present embodiment, as shown in FIGS. 1 to 3, the positive electrode lead portion 123 of the positive electrode 12 is a part of the positive electrode current collector terminal 121 extending across the first side 111 of the separator 11, and It extends downward in the figure. The negative electrode lead portion 133 of the negative electrode 13 is a part of the negative electrode current collecting terminal 131 extending across the second side 112 of the separator 11 located on the opposite side of the first side 111. It extends to. That is, the positive electrode lead portion 123 of the positive electrode 12 and the negative electrode lead portion 133 of the negative electrode 13 extend in opposite directions.

  The separator 11 has a bonding region K that is intermittently bonded in each layer of the core 10 so that the bonding portions M and the non-bonding portions S are alternately formed with respect to at least one separator 11 adjacent in the stacking direction. Have. The junction region K includes a first junction region K1 in which the first sides 111 are intermittently joined and a second junction region K2 in which the second sides 112 are intermittently joined. In the case of the present embodiment, as shown in FIG. 2, the adhesive portions M and the non-adhesive portions S alternate at least along the side opposite to the side where the positive electrode lead portion 123 extends, that is, the second side 112. The second bonding region K2 that is intermittently bonded so as to be aligned is formed, and the bonding portion M is not bonded along the side opposite to the side where the negative electrode lead portion 133 extends, that is, the first side 111. A first junction region K1 that is intermittently joined so as to be alternately arranged with the portions S is formed.

  Note that the bonding portion M is bonded so that sufficient heat for melting and bonding the separator 11 is supplied and local heat shrinkage is not caused. Therefore, it may be welded by a laser beam or ultrasonic waves other than the thermal welding by the conventional heater. Alternatively, they may be joined by an adhesive or the like. In this specification, melting and joining with heat is referred to as “welding”. It may be “fusion” in which the material itself is melted and joined.

  When attention is paid to one separator 11, the separator 11 is bonded to the one-side separator adjacent on one side in the stacking direction in the first bonding region K <b> 1, and the other separator adjacent on the opposite side in the stacking direction. Are joined in the second joining region K2. In other words, when the separator 11 is intermittently joined to the separator 11 adjacent on one side in the stacking direction along one of the four sides of the outer periphery of the positive electrode 12 and the negative electrode 13, the joined one side Are intermittently joined to the adjacent separator 11 on the opposite side in the stacking direction. In the case of the present embodiment, as shown in FIG. 2, the separator 11 in which the first side 111 is intermittently bonded to the side opposite to the side where the negative electrode lead portion 133 crosses, that is, the bonded first side 111. The second side 112, which is the opposite side, is intermittently joined to the adjacent separator 11 on the opposite side in the stacking direction. The separator 11 joined to the leftmost separator 11 shown in FIG. 2 at the first side 111, that is, the second separator 11 shown from the left in FIG. It is joined to the separator 11 located on the opposite side to the separator 11 in the stacking direction, that is, the third separator 11 from the left in FIG. In this way, one separator 11 is joined at a position opposite to the separator 11 joined on one side and a different separator 11 on the opposite side in the stacking direction.

  Further, in the present embodiment, as shown in FIG. 3, the third side 113 orthogonal to the first side 111 and the second side 112 and the fourth side 114 which is the opposite side are also intermittently provided. A joined region K is formed. In each side, the bonding portion M has a width in a direction away from the outer periphery of the positive electrode 12 and the negative electrode 13, that is, in a direction crossing each side.

  In the secondary battery configured as described above, the portion where the separator 11 is joined in the stacking direction is such that the bonding portions M and the non-bonding portions S are alternately arranged along the outer peripheral sides of the positive electrode 12 and the negative electrode 13. It has the joining area | region K joined intermittently. And the joining area | region K joins the 1st joining area | region K1 which joins the 1st edge | side 111 of the separator 11 adjacent in a lamination direction, and the 2nd edge | side 112 of the separator 11 adjacent in a lamination direction. And at least the second junction region K2. Therefore, when the temperature of the secondary battery 1 is excessively increased due to abnormal overheating, the separator 11 can be prevented from contracting along the planes of the positive electrode 12 and the negative electrode 13 due to the heat.

  Further, in the secondary battery 1 of the first embodiment, the positive electrode current collector terminal 121 intersects the first side 111 and extends outward from the outer periphery of the separator 11, and the negative electrode current collector terminal 131 is the second current collector terminal 131. It intersects the side 112 and extends outside the outer periphery of the separator 11. A first bonding region K1 is provided on the first side 111, and a second bonding region is provided on the second side 112. That is, it is possible to effectively prevent the separator 11 from contracting in the direction in which the electrode lead that is a part of each current collecting terminal extends, and to prevent the electrodes from contacting each other.

  Since the adhesive portion M is provided intermittently, even if the separator 11 contracts and tears from the adhesive portion M as a starting point, the adhesive portion M is only partially avoided and is torn over a wide range. Can be suppressed.

  Even if gas is generated from the positive electrode 12 and the negative electrode 13 of the secondary battery 1, the separator 11 of the secondary battery 1 is intermittently joined to the adjacent separator 11. It is easy to be discharged out of the core 10 through S. By discharging to the nearest outer peripheral portion from the position where the gas is generated, deformation of the secondary battery 1 can be suppressed.

  Hereinafter, secondary batteries 1 according to second to sixth embodiments of the present invention will be described with reference to the drawings. Configurations having the same functions as those of the secondary battery 1 of the first embodiment use the same reference numerals, and in each drawing, are given the same reference numerals, and the detailed description corresponds to the description of the first embodiment. And, if necessary, refer to the drawings.

  A secondary battery 1 according to a second embodiment of the present invention will be described with reference to FIGS. The secondary battery 1 is provided with respect to separators 11 adjacent to each other in the stacking direction so that adhesive portions M and non-adhesive portions S are alternately formed along at least one of the four sides of the outer periphery of the positive electrode 12 and the negative electrode 13. Intermittently joined. In the second embodiment, when attention is paid to one separator 11, the separator 11 that is intermittently bonded on one of the four sides of the outer periphery of the positive electrode 12 and the negative electrode 13 is further laminated in the stacking direction on the opposite side of the bonded one side. Are intermittently joined to separators adjacent to each other.

  In the case of the second embodiment, as shown in FIG. 4, the separator 11 joined at the first side 111 is intermittently joined to the same separator 11 also at the second side 112 located on the opposite side. In other words, the separators 11 adjacent to each other in the stacking direction via the negative electrode 13, that is, the separators 11 sandwiching the negative electrode 13 are intermittently joined at the first side 111 and the second side 112. A portion where the negative electrode lead portion 133 of the negative electrode 13 crosses the second side 112 cannot be welded. Therefore, the required bonding strength is ensured by increasing the bonding area of the bonding portion M disposed immediately adjacent to the negative electrode lead portion 133.

  Similarly to the first embodiment, the third side 113 and the fourth side 114 are also provided with a bonding region K in which an adhesive portion M is provided intermittently so as to surround the negative electrode 13. In order to maintain the relative position between the positive electrode 12 and the negative electrode 13, the third side 113 and the fourth side 114, which is the opposite side, are adjacent to each other in the stacking direction via the positive electrode 12, that is, the positive electrode 12 is The sandwiching separators 11 may be joined intermittently.

  Since the secondary battery 1 of the second embodiment configured as described above is joined so that the separator 11 sandwiches the negative electrode 13 on each of the first side 111 side and the second side 112 side, The negative electrode 13 can suppress the temperature of the secondary battery 1 from increasing due to overheating and causing the separator 11 to contract. Even if gas is generated around the positive electrode 12 and the negative electrode 13 surrounded by the separator 11, since the separator 11 is intermittently joined, it is discharged out of the core through the non-bonded portion S.

  A secondary battery 1 according to a third embodiment of the present invention will be described with reference to FIG. In the core 10 of the secondary battery 1 shown in FIG. 6, the adhesive portion MA of the separator 11 located in a range facing the safety valve 21 provided on the outer peripheral wall of the container 2 is set in a direction along the outer periphery of the positive electrode 12 and the negative electrode 13. , And smaller than the adhesion part M outside this range. Further, the non-adhesive portion SA provided in the range facing the safety valve 21 is made larger than the non-adhesive portion S outside this range in the direction along the outer circumference of the positive electrode 12 and the negative electrode 13. That is, the space | interval which arrange | positions the adhesion part MA of the range which opposes the safety valve 21 is expanded.

  In the direction along the outer periphery of the separator 11, the length of the normal bonded portion M is ML1, the length of the bonded portion MA in the range facing the safety valve 21 is ML2, the length of the normal non-bonded portion S is SL1, and the safety valve When the lengths of the non-adhesive portions SA in the range opposite to 21 are defined as SL2, ML1> ML2 and SL1 <SL2. Furthermore, it is also preferable that the length SL2 of the non-bonded portion SA is larger than the length ML2 of the bonded portion MA in the range facing the safety valve 21, that is, ML2 <SL2.

  As described above, the aperture ratio is increased by shortening the length ML2 of the bonded portion MA in the range facing the safety valve 21 and increasing the length SL2 of the non-bonded portion SA. In order to secure the bonding strength of the individual bonded portions M, only the interval between the bonded portions M may be increased without changing the size of the bonded portions M, that is, the non-bonded portion SA may be increased.

  By expanding the non-adhesive portion SA in a range facing the safety valve 21, the gas generated inside the core can be easily discharged to the safety valve 21 side. By positively releasing the generated gas to the safety valve 21 side, the separator 11 is prevented from being damaged.

  A secondary battery 1 according to a fourth embodiment of the present invention will be described with reference to FIG. In the core 10 of the secondary battery 1 shown in FIG. 7, the bonding portion M provided on the third side 113 of the separator 11 and the fourth side 114 that is the opposite side is separated from the outer periphery of the positive electrode 12 and the negative electrode 13. It has a width. And the welding length ML3 of the inner peripheral side of the adhesion part M is formed smaller in the direction along the outer periphery of the positive electrode 12 and the negative electrode 13 than the welding length ML4 of the outer peripheral side. That is, the adhesion part M is formed in a trapezoid whose inner peripheral side is shorter than the outer peripheral side. In other words, the length SL3 on the inner peripheral side of the non-bonded portion S is larger than the length SL4 on the outer peripheral side.

  By forming the adhesion part M and the non-adhesion part S in this way, the gas generated inside the core 10 can be easily released to the outside through the non-adhesion part S, and between the core 10 and the container 2. It is possible to prevent fine objects such as metal pieces mixed during manufacture from entering the core 10. Therefore, it is more preferable that the welding length ML4 on the outer peripheral side of the bonded portion M is larger than the length SL4 on the outer peripheral side of the non-bonded portion S.

  A secondary battery 1 according to a fifth embodiment of the present invention will be described with reference to FIG. In the core 10 of the secondary battery 1 shown in FIG. 8, the shape of the adhesive part M is different from that of the fourth embodiment. The weld length ML3 on the inner peripheral side of the adhesive part M of the fifth embodiment is substantially zero, and therefore the shape of the adhesive part M is a triangle having a vertex on the inner peripheral side as shown in FIG. . By forming the bonding portion M in this way, the gas generated inside the core 10 is easily discharged without being obstructed by the bonding portion M when moving toward the outside of the core 10.

  A secondary battery 1 according to a sixth embodiment of the present invention will be described with reference to FIGS. 9 and 10. In the core 10 of the secondary battery 1 shown in FIG. 9 and FIG. 10, the separator 11 is the second of the separators 11 adjacent to each other in the electrode stacking direction on both the first side 111 side and the second side 112 side. The first side 111 and the second side 112 are joined intermittently in the direction. At this time, in order to increase the bonding strength between the separators 11 in a range where the positive electrode current collector terminal 121 and the negative electrode current collector terminal 131 cross, at least the outer peripheral edge of the separator 11 In the range crossing the bonding region K formed in this, in this case, the range crossing the first bonding region K1 and the second bonding region K2, the coupling portions 124, 134 constituted by a plurality of holes penetrating in the stacking direction. Is provided. As shown in FIG. 11, the coupling portions 124 and 134 may have a large number of round holes such as a so-called punching plate, or an opening having the same area as the bonding area of the bonding portion M is arranged. Just be there.

  Since the positive electrode current collector terminal 121 and the negative electrode current collector terminal 131 have the coupling portions 124 and 134, the separator 11 can be welded with the positive electrode current collector terminal 121 and the negative electrode current collector terminal 131 sandwiched in the stacking direction. . The separator 11 is welded through the coupling portions 124 and 134, whereby the separator 11 is fixed to the positive electrode current collector terminal 121 and the negative electrode current collector terminal 131. At this time, the separator 11 is fixed to the positive electrode current collector terminal 121 at the first side 111 and is fixed to the negative electrode current collector terminal 131 at the second side 112. That is, since a pair of opposite sides is fixed to the separator 11, it can suppress that the separator 11 shrink | contracts with a heat | fever.

  Furthermore, according to the secondary battery 1 of this embodiment, the second sides 112 of the separator 11 located on the side opposite to the positive electrode current collecting terminal 121, and the second side 112 of the separator 11 located on the side opposite to the negative electrode current collecting terminal 131 are used. At the same time as joining one side 111 to each other, the coupling portions 124 and 134 of the positive current collecting terminal 121 and the negative current collecting terminal 131 can be stacked and welded in the stacking direction. That is, since the positive electrode 12 and the negative electrode 13 can be stacked together after the separator 11 is sandwiched therebetween, the productivity of the core 10 and the productivity of the secondary battery 1 are improved.

  The first to sixth embodiments described above can be implemented in any combination. For example, the size of the bonded portion M and the non-bonded portion S in the range facing the safety valve 21 as in the third embodiment is changed, or the shape of the bonded portion M is changed as in the fourth and fifth embodiments. Such changes can be applied to other embodiments.

  DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 2 ... Container, 21 ... Safety valve, 10 ... Core, 11 ... Separator, 111 ... 1st edge | side, 112 ... 2nd edge | side, 12 ... Positive electrode, 121 ... Positive electrode current collection terminal, 123 ... Positive electrode Lead part, 13 ... negative electrode, 131 ... negative electrode current collecting terminal, 133 ... negative electrode lead part, 124, 134 ... coupling part, K ... joining region, K1 ... first joining region, K2 ... second joining region.

Claims (6)

A secondary battery comprising a core formed by alternately laminating positive and negative electrodes with a separator having a first side and a second side located on the opposite side in between,
The separator has a bonding region that is intermittently bonded in each layer of the core so that an adhesive portion and a non-adhesive portion are alternately formed with respect to at least one separator adjacent in the stacking direction,
The junction region, viewed contains a first junction region in which the first side to each other are intermittently joined, a second junction region in which the second sides each other are intermittently joined, the,
The positive electrode and the negative electrode include a positive electrode current collector terminal and a negative electrode current collector terminal that intersect the first side or the second side and extend outward from the outer periphery of the separator. Secondary battery. The separator is bonded to the one-side separator adjacent on one side in the stacking direction at the first bonding region, and bonded to the opposite separator adjacent on the opposite side in the stacking direction at the second bonding region. The secondary battery according to claim 1, wherein: A container that stores the core, and a safety valve that is opened when an internal pressure set on an outer peripheral wall of the container is exceeded,
The adhesive portion provided in the range facing the safety valve is smaller in the direction along the outer periphery of the positive electrode and the negative electrode than the adhesive portion provided in the other range,
The non-adhesive part provided in the range facing the safety valve is larger in the direction along the outer periphery of the positive electrode and the negative electrode than the non-adhesive part provided in the other range. The secondary battery described in 2. The adhesive portion has a width in a direction away from the outer periphery of the positive electrode and the negative electrode, and an adhesive length on the inner peripheral side of the separator in a direction along the outer periphery of the positive electrode and the negative electrode is the outer peripheral side of the separator 4. The secondary battery according to claim 1, wherein the secondary battery is smaller than an adhesion length of the secondary battery. 5. 5. The secondary battery according to claim 4, wherein an adhesion length on an outer peripheral side of the separator in the adhesion portion is larger than a non-adhesion length on an outer circumference side of the separator in the non-adhesion portion. The positive electrode current collector terminal and the negative electrode current collector terminal each have a coupling portion provided with a plurality of holes penetrating in the stacking direction in a range crossing at least the joining region,
2. The secondary battery according to claim 1 , wherein the separator is bonded to the separators adjacent to each other in the stacking direction through the coupling portion of the positive current collector terminal and the negative current collector terminal.

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