JP2016103359A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce material cost by eliminating waste of electrode (positive electrode or negative electrode) or separator.SOLUTION: In a secondary battery as a power storage device, a flat electrode assembly 12 where a strip positive electrode 13 and a strip negative electrode 14, wound while interposing a strip separator 15, is housed in a case. Ends 13c, 14c, 15a of the positive electrode 13, negative electrode 14 and separator 15 are arranged in one bend 12b of the electrode assembly 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power storage device, and more particularly, to a power storage device including a flat wound electrode assembly.

  In a power storage device including a flat wound electrode assembly, an electrode assembly wound in a state where a strip-shaped separator is interposed between a strip-shaped positive electrode and a strip-shaped negative electrode is housed in a case. . The electrode assembly is accommodated in the case in a state of being constrained to the inner surface of the case at the planar portions on both sides in the thickness direction. When the terminal ends of the strip-shaped positive electrode and the strip-shaped negative electrode are arranged on the planar portion of the electrode assembly, a step is formed on the surface of the planar portion, and the pressure when the planar portion of the electrode assembly is constrained by the case is low. It becomes uniform. As a result, cycle characteristics are degraded.

  In Patent Document 1, in the wound electrode assembly, the winding terminal portions of the belt-like positive electrode and the belt-like negative electrode are both arranged at positions deviating from the portion of the electrode assembly that substantially receives the restraining load. An electrode assembly is disclosed. As a particularly preferable arrangement of the terminal portions of the positive electrode, the negative electrode, and the separator, any one of the terminal portions of the positive electrode, the negative electrode, and the separator is formed between the two flat surfaces of the electrode assembly. It is mentioned that it is arrange | positioned at the corner part (R part) of this, and the remaining termination | terminus part is arrange | positioned at the other corner part.

Japanese Patent No. 4630855

  However, when the terminal portions of the positive electrode and the negative electrode are arranged at different corners, the negative electrode and the separator are wasted more than half a round with respect to the positive electrode. Moreover, when the terminal part of a positive electrode and a negative electrode is arrange | positioned in the same corner part, a separator will be wasted more than half a circle.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an electricity storage provided with a flat wound electrode assembly that can reduce material costs by eliminating waste of electrodes and separators. To provide an apparatus.

  A power storage device that solves the above problem is a power storage device in which a flat electrode assembly wound in a state where a strip-shaped separator is interposed between a strip-shaped positive electrode and a strip-shaped negative electrode is housed in a case, Terminal ends of the positive electrode, the negative electrode, and the separator are disposed on one curved portion of the electrode assembly. Here, the “end” means an end in the winding direction. According to this configuration, waste of electrodes and separators can be eliminated and material costs can be reduced.

  The separator is preferably wound more than one round than the positive electrode and the negative electrode. In the configuration in which the separator is wound the same number of times as the positive electrode and the negative electrode, the portion disposed on the outermost periphery of the electrodes constituting the wound body of the positive electrode, the negative electrode, and the separator is the wall surface of the case via only one layer of separator. Is pressed by. And since the thickness of the separator is as thin as 10 microns (for example, about 20 μm), depending on the material and thickness of the separator, it may be broken when the electrode assembly is handled, and the electrode may be scratched or wrinkled. If the electrode assembly is restrained in this state, the pressure becomes non-uniform, which may lead to deterioration of cycle characteristics. However, when the separator is wound more than one round from the end of the positive electrode and the negative electrode, it is possible to prevent the electrode from being scratched or wrinkled regardless of the material and thickness of the separator.

  The electrode assembly is accommodated in the case in a state in which the top of the one curved portion is in contact with the inner surface of the case, and the end of the separator exceeds the end of the positive electrode and the negative electrode, and the positive electrode In the winding direction of the negative electrode and the separator, it is preferable that the negative electrode and the separator are arranged at positions on the front side of the top. Here, “the front side more than the top” means the top or the front side from the top.

  The electrode assembly expands when the power storage device is charged. At this time, the terminal end of the separator exceeds the terminal end of the positive electrode and the negative electrode and is located at the top of the curved portion or the position beyond the top. When the swell expands, the end of the separator or near the end is pressed against the inner surface of the case. Therefore, occurrence of winding deviation of the separator, the positive electrode, and the negative electrode is prevented when the electrode assembly is expanded.

  The end of the separator is determined by the distance between the welding range of the positive electrode and the positive electrode conductive member, the negative electrode and the negative electrode conductive member, and the end of the separator in the winding circumferential direction. It is preferable that the material layer is disposed at a distance greater than or equal to the distance between the active material layer and the distance between the negative electrode and the negative electrode conductive member. Here, “the welding range of the positive electrode and the positive electrode conductive member and the negative electrode and the negative electrode conductive member” means both ends of the welded portion of the positive electrode and the positive electrode conductive member and the welded portion of the negative electrode and the negative electrode conductive member in the winding direction of the separator. It means a range between two straight lines connecting the parts. According to this configuration, the heat radiation proceeds until the heat generated at the welding point is transmitted to the end of the separator via the metal foil constituting the positive electrode or the negative electrode, and the deformation of the separator due to the heat during welding is prevented. . In addition, it is possible to prevent the separator from being loosened by vibration when welding is performed by ultrasonic welding.

When the radius of curvature of the surface of the curved portion of the electrode assembly is r, the end of the separator is (2 ¹⁾ from the welded portion between the case main body of the case and the lid that covers the opening of the case main body. ^/ 2-1) It is arranged at a position separated by r or more. According to this configuration, the heat generated at the welding location when the case body and the lid body are welded is dissipated before being transmitted to the end of the separator via the metal foil constituting the lid body, the case body, and the positive electrode or the negative electrode. Advances and deformation due to heat is suppressed. Further, the occurrence of slack in the separator due to vibration when welding is performed by ultrasonic welding is also suppressed.

The end of the separator is disposed at a position that is a distance greater than or equal to the radius of curvature of the surface of the curved portion of the electrode assembly from the weld location between the case main body of the case and the lid that covers the opening of the case main body. Has been. According to this configuration, the distance becomes larger than that in the case of (2 ^1/2 −1) r, and is less susceptible to the heat generated at the welding location.

  According to the present invention, waste of electrodes and separators can be eliminated and material costs can be reduced.

(A) is a schematic perspective view of a secondary battery, (b) is a schematic cross section. (A) is a partial expansion schematic perspective view of an electrode assembly, (b) is a schematic cross-sectional view of an electrode assembly. The schematic perspective view which shows the welding range of a positive electrode, a positive electrode electrically-conductive member, and a negative electrode and a negative electrode electrically-conductive member. (A) is a schematic perspective view which shows the relationship between metal foil and a welding location, (b) is a schematic cross section which shows the relationship between metal foil (active material uncoated part), a welding location, and an active material layer. The schematic diagram which shows the force which acts on an electrode assembly when an electrode assembly expand | swells. The schematic perspective view which shows the relationship between the positive electrode electrically-conductive member at the time of welding, the negative electrode electrically-conductive member, and an electrode assembly. (A) is a schematic cross section of the secondary battery of another embodiment, (b) is a plan view omitting the lid and nut.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIGS. 1 (a) and 1 (b), a secondary battery 10 as a power storage device is provided in a rectangular box-shaped case 11 composed of a case body 11a and a lid body 11b covering the opening. A wound-type electrode assembly 12 and an electrolytic solution (not shown) are accommodated. The electrode assembly 12 is accommodated in the case 11 in a state in which the winding shaft is in the lateral direction of the case 11 (the left-right direction in FIG. 1B). The case body 11a and the lid body 11b are joined by welding. The welding is performed by, for example, resistance welding, ultrasonic welding, or laser welding.

  As shown in FIGS. 2A and 2B, the electrode assembly 12 has a structure in which the electrode assembly 12 is flatly wound with a strip-shaped separator 15 interposed between the strip-shaped positive electrode 13 and the strip-shaped negative electrode 14. Have. That is, the electrode assembly 12 is configured such that two linear portions 12a are continuous at both ends via two curved portions (R portions) 12b.

  As shown in FIG. 2A, the positive electrode 13 includes a positive electrode active material layer 13a in which a positive electrode active material is applied to a strip-shaped metal foil 16, and an active material uncoated portion 13b in which no positive electrode active material is applied. Have. The negative electrode 14 includes a negative electrode active material layer 14a in which a negative electrode active material is applied to a strip-shaped metal foil 16, and an active material uncoated portion 14b in which no negative electrode active material is applied.

  Two separators 15 are used, one positive electrode 13 and one negative electrode 14 are used, and the separator 15 exists on the outermost periphery of the electrode assembly 12. The negative electrode 14 is wound with a separator 15 between the positive electrode 13 and the negative electrode 14. That is, the negative electrode 14 is positioned outside the positive electrode 13 on the outer peripheral side of the electrode assembly 12, and is positioned inside the positive electrode 13 on the innermost periphery of the electrode assembly 12. The winding start of the negative electrode 14 and the winding start of the positive electrode 13 are positioned so as to face the same curved portion 12 b of the electrode assembly 12. When the secondary battery 10 is a lithium ion secondary battery, the metal foil 16 for the positive electrode 13 is preferably an aluminum foil, and the metal foil 16 for the negative electrode 14 is preferably a copper foil.

  As shown in FIG. 2B, the terminal end 13 c of the positive electrode 13, the terminal end 14 c of the negative electrode 14, and the terminal end 15 a of the separator 15 are disposed on one curved portion 12 b of the electrode assembly 12. Each of the terminal ends 13c, 14c, and 15a is disposed at a position near the front end portion in the winding direction of the curved portion 12b (boundary with the straight portion 12a), the terminal end 15a of the separator 15 is positioned at the foremost side, and the negative electrode 14 end 14c and positive electrode 13 end 13c. The separator 15 is wound more than one round than the positive electrode 13 and the negative electrode 14.

  The electrode assembly 12 is housed in the case 11 with the top 12t of one curved portion 12b in contact with the inner surface of the case 11, and the terminal 15a of the separator 15 is connected to the terminals 13c and 14c of the positive electrode 13 and the negative electrode 14, respectively. In the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15, the top portion 12 t is disposed at the front side. In this embodiment, each end 13c, 14c, 15a is disposed at a position beyond the top 12t of one curved portion 12b.

  As shown in FIGS. 1A and 1B, the secondary battery 10 includes a positive electrode terminal 17 and a negative electrode terminal 18. The positive terminal 17 and the negative terminal 18 are provided so as to protrude from the lid 11b. The positive electrode terminal 17 and the active material uncoated portion 13 b are electrically connected by a positive electrode conductive member 19. The negative electrode terminal 18 and the active material uncoated portion 14 b are electrically connected by a negative electrode conductive member 20. The secondary battery 10 exchanges electricity with the electrode assembly 12 through the positive electrode terminal 17 and the negative electrode terminal 18.

  The positive electrode terminal 17 and the negative electrode terminal 18 have male screw portions 17a and 18a and flange portions 17b and 18b. The positive electrode conductive member 19 is welded to the lower surface of the flange portion 17b, and the negative electrode conductive member 20 is welded to the lower surface of the flange portion 18b. Has been. The positive electrode terminal 17 and the negative electrode terminal 18 have the male screw portions 17a and 18a pass through the holes formed in the lid body 11b with the flange portions 17b and 18b positioned inside the case 11, and the male screw portions 17a and 18a. It is fastened and fixed to the lid 11b by a nut 21 that is screwed onto the lid 11b.

  A seal member 22 made of an electrically insulating material is interposed between the nut 21 and the lid body 11b, and a seal made of an electrically insulating material (not shown) is interposed between the flange portions 17b and 18b and the lid body 11b. A member is interposed. In addition, the positive terminal 17 and the negative terminal 18 are configured so that a bus bar for electrically connecting a plurality of secondary batteries 10 can be fastened and fixed with bolts, so that a female screw hole ( (Not shown) is provided.

  As shown in FIGS. 1A and 1B, the electrode assembly 12 includes a positive electrode conductive member 19 and a curved portion 12b where the terminal end 13c of the positive electrode 13, the terminal end 14c of the negative electrode 14, and the terminal end 15a of the separator 15 are arranged. It is welded to the positive electrode conductive member 19 and the negative electrode conductive member 20 in a state opposite to the side corresponding to the negative electrode conductive member 20, that is, the side corresponding to the bottom of the case body 11a.

  The terminal end 15a of the separator 15 is the distance L1 in the winding circumferential direction between the positive electrode 13, the positive electrode conductive member 19, the negative electrode 14 and the negative electrode conductive member 20, and the terminal end 15a of the separator 15, and the positive electrode 13 and the positive electrode conductive member. 19 and the distance between the welded portion 19a and the positive electrode active material layer 13a and the distance between the negative electrode 14 and the negative electrode conductive member 20 between the welded portion 20a and the negative electrode active material layer 14a. The welding range 23 of the positive electrode 13 and the positive electrode conductive member 19 and the negative electrode 14 and the negative electrode conductive member 20 is, as shown by a two-dot chain line in FIG. 3, a welded portion 19 a between the positive electrode 13 and the positive electrode conductive member 19, and the negative electrode 14 and the negative electrode. It means a range sandwiched by lines connecting the upper ends and the lower ends of the welded portion 20a with the conductive member 20.

  Next, a method for manufacturing the secondary battery 10 configured as described above will be described. The method for manufacturing the secondary battery 10 includes the step of manufacturing the electrode assembly 12 and the electrode assembly 12 and the positive electrode terminal 17 and the negative electrode terminal 18 are electrically connected via the positive electrode conductive member 19 and the negative electrode conductive member 20. A process, a process of accommodating the electrode assembly 12 in the case 11, and a process of welding the case main body 11a and the lid body 11b.

  In the process of manufacturing the electrode assembly 12, the negative electrode 14 becomes the inner side in a state where the strip-shaped positive electrode 13, the strip-shaped negative electrode 14 and the strip-shaped separator 15 are laminated in the order of the positive electrode 13, the separator 15, the negative electrode 14, and the separator 15. Wind in a flat state. Specifically, as shown in FIG. 2B, the winding start positions of the positive electrode 13, the negative electrode 14, and the separator 15 are set to positions facing the same curved portion 12 b of the electrode assembly 12. Then, as shown in FIG. 2B, the end 15a of the two separators 15, the end 14c of the negative electrode 14, and the end 13c of the positive electrode 13 are arranged in this order in the winding direction in one curved portion 12b of the electrode assembly 12. The electrode assembly 12 arranged so as to be close to the front end is manufactured. The terminal end 15a of the separator 15 is fixed to the lower separator 15 with an adhesive tape (not shown), or fixed to the lower separator 15 with an adhesive or a pressure-sensitive adhesive.

  In the step of electrically connecting the electrode assembly 12 to the positive electrode terminal 17 and the negative electrode terminal 18 via the positive electrode conductive member 19 and the negative electrode conductive member 20, first, the positive electrode terminal 17, the positive electrode conductive member 19, the negative electrode 14, and the negative electrode conductive member. Welding with 20 is performed. Next, the active material uncoated portion 13b of the positive electrode 13 and the positive electrode conductive member 19 and the active material uncoated portion 14b of the negative electrode 14 and the negative electrode conductive member 20 are welded.

  When welding the positive electrode 13 and the positive electrode conductive member 19 and the negative electrode 14 and the negative electrode conductive member 20, the heat generated at the welded portions 19 a and 20 a is transferred to the separator 15 via the metal foil 16 constituting the positive electrode 13 or the negative electrode 14. Communicated. When most of the heat generated at the welded portions 19a and 20a reaches the position corresponding to the end 15a of the separator 15 through the metal foil 16, the separator 15 may be thermally deformed. However, the end 15a of the separator 15 is such that the distance L1 between the welding range 23 and the end 15a of the separator 15 in the winding circumferential direction is the distance between the welded portion 19a between the positive electrode 13 and the positive electrode conductive member 19 and the positive electrode active material layer 13a. And it arrange | positions in the location which becomes more than the distance of the welding location 20a of the negative electrode 14 and the negative electrode electrically-conductive member 20, and the negative electrode active material layer 14a. Therefore, heat radiation proceeds until the heat generated in the welded portions 19a and 20a reaches the position corresponding to the end 15a of the separator 15 on the metal foil 16, and the generated heat corresponds to the end 15a of the separator 15. At the time when it is transmitted to the position, the amount of heat is smaller than the amount by which the separator 15 is thermally deformed.

  More specifically, for example, the metal foil 16 at the welded portion 19a between the active material uncoated portion 13b of the positive electrode 13 and the positive electrode conductive member 19 is schematically illustrated in FIG. FIG. 4B schematically shows a cross section of the welded portion 19a cut in the thickness direction of the electrode assembly 12 on a plane parallel to the winding axis direction of the electrode assembly 12. As shown in FIG.

  As shown in FIG. 4 (b), the metal foil 16 (active material uncoated portion 13b) of the positive electrode 13 has a minimum distance (adherence state) between a distance L2 from the welded portion 19a to the positive electrode active material layer 13a. It will be in the state which extends to the maximum interval. And while the heat which generate | occur | produced in the welding location 19a is transmitted to the position corresponding to the positive electrode active material layer 13a from the welding location 19a, it is thermally radiated from the clearance gap between the adjacent metal foils 16. FIG. Further, the heat generated at the welded portion 19a is transmitted not only in the direction in which the positive electrode active material layer 13a exists, but also in the direction toward the curved portion 12b (the left-right direction in FIG. 4A). In the metal foil 16 (active material uncoated portion 13b) in the direction from the welded portion 19a toward the curved portion 12b, the distance between the adjacent metal foils 16 increases as the distance from the welded portion 19a increases in the range close to the welded portion 19a. Therefore, the heat generated at the welded portion 19a is radiated from the gap between the adjacent metal foils 16 even when transmitted toward the curved portion 12b. As a result, the heat generated at the welded portion 19a is reduced to a state where there is no adverse effect on the separator 15 while being transferred to the portion where the terminal end 15a of the separator 15 exists.

  Similarly, while the heat generated at the welded portion 20a between the active material uncoated portion 14b of the negative electrode 14 and the negative electrode conductive member 20 is transferred to the portion where the terminal end 15a of the separator 15 exists, the separator 15 To a state where there is no adverse effect on

  In the process of housing the electrode assembly 12 in the case 11, the positive electrode terminal 17 to which the positive electrode conductive member 19 is welded and the negative electrode terminal 18 to which the negative electrode conductive member 20 is welded are connected to each other through a seal member 22 and a nut 21. The lid-electrode assembly ASSY assembled to 11b is assembled. Next, the lid assembly-electrode assembly ASSY is supported by the lid body 11b, and the electrode assembly 12 is held in the case 11 with the winding axis direction of the electrode assembly 12 held parallel to the bottom surface of the case body 11a. Insert inside. The electrode assembly 12 is inserted into the case 11 with the outer surface of the straight portion 12a being in contact with the inner surface of the case body 11a and being restrained by the inner surface of the case body 11a.

  The insertion of the electrode assembly 12 into the case body 11a is completed, and a process of welding the case body 11a and the lid body 11b is performed in a state where the lid body 11b is in contact with the case body 11a. The case 11 is sealed by welding to the case main body 11a. Since the terminal end 15a of the separator 15 is disposed in the curved portion 12b of the electrode assembly 12 facing the bottom wall of the case main body 11a, the welding portion is welded to the case main body 11a and the lid 11b. Not affected by the heat generated from

Then, after a predetermined amount of electrolyte is injected into the case 11 from a not-shown pouring port, the pouring port is sealed, and the secondary battery 10 is completed.
Next, the operation of the secondary battery 10 configured as described above will be described.

  Although the secondary battery 10 is used alone, it is generally used as an assembled battery in which a plurality of secondary batteries 10 are connected in series or in parallel. The secondary battery 10 is used for various applications. For example, the secondary battery 10 is mounted on a vehicle and used as a power source for a traveling motor or a power source for other electrical devices.

  The electrode assembly 12 expands during charging. When the terminal ends 13c and 14c of the positive electrode 13 and the negative electrode 14 are disposed on the straight portion 12a of the electrode assembly 12, the surface (outer surface) of the straight portion 12a is located at a position corresponding to the terminal portions 13c and 14c of the positive electrode 13 and the negative electrode 14. A step portion is generated. Since the electrode assembly 12 is constrained by the inner surface of the case body 11a on the surface of the straight portion 12a, if there are stepped portions due to the terminal portions 13c and 14c of the positive electrode 13 and the negative electrode 14 on the surface of the straight portion 12a, the electrode assembly 12 is provided. When the battery expands, force is applied to the positive electrode 13 and the negative electrode 14 from the case body 11a in a non-uniform manner, leading to a decrease in cycle characteristics of the secondary battery 10. However, since the terminal ends 13c and 14c of the positive electrode 13 and the negative electrode 14 are not disposed on the straight line portion 12a, the electrode assembly 12 is removed from the case body 11a at a position corresponding to the terminal ends 13c and 14c of the positive electrode 13 and the negative electrode 14. The non-uniform pressure which leads to the deterioration of the cycle characteristics of the secondary battery 10 is not received.

  In the configuration in which the separator 15 is wound the same number of times as that of the negative electrode 14, the portion disposed on the outermost periphery of the negative electrode 14 constituting the electrode assembly 12 is the wall surface of the case 11 via only one layer of separator 15. It is pressed by. Since the separator 15 is as thin as 10 microns (for example, about 20 μm), depending on the material and thickness of the separator 15, the separator 15 may be broken when the electrode assembly 12 is handled, and the negative electrode 14 may be damaged or flawed. There is a case. If the electrode assembly 12 is constrained in this state, the pressure becomes non-uniform, which may lead to deterioration of cycle characteristics. However, since the separator 15 is wound more than one round than the positive electrode 13 and the negative electrode 14, the negative electrode 14 is prevented from being scratched or flawed regardless of the material and thickness of the separator 15, and the negative electrode 14 is damaged. Deterioration of the cycle characteristics due to or wrinkles is prevented.

  The electrode assembly 12 expands when the secondary battery 10 is charged. However, the end 15 a of the separator 15 is disposed at a position that is more than the top 12 t in the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15 in the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15. In this embodiment, each end 13c, 14c, 15a is disposed at a position beyond the top 12t of one curved portion 12b. Therefore, when the electrode assembly 12 expands, the vicinity of the terminal end 15a of the separator 15 is pressed against the inner surface of the case 11 at the top 12t of the curved portion 12b. As a result, when the electrode assembly 12 expands, the separator 15 is prevented from being unwound, and thus the positive electrode 13 and the negative electrode 14 are not wound.

  When the electrode assembly 12 is expanded, a reaction force in which the top portion 12t of the curved portion 12b presses the bottom wall of the case 11 is applied to the electrode assembly 12 in the arrow Y1 direction, as shown in FIG. When the electrode assembly 12 is moved by this reaction force, stress is applied to the welding location (connection location) 19 a between the positive electrode 13 and the positive electrode conductive member 19 and the welding location (connection location) 20 a between the negative electrode 14 and the negative electrode conductive member 20. It takes. However, since the electrode assembly 12 is prevented from moving due to the force F generated by the expansion of the electrode assembly 12 in the thickness direction, the force applied from the bottom wall of the case 11 is applied to the welded portions 19a and 20a as stress. Is prevented.

According to this embodiment, the following effects can be obtained.
(1) A secondary battery 10 serving as a power storage device includes a flat electrode assembly 12 wound in a state where a strip-shaped separator 15 is interposed between a strip-shaped positive electrode 13 and a strip-shaped negative electrode 14. Is housed in. In addition, the positive electrode 13, the negative electrode 14, and the terminal ends 13 c, 14 c, 15 a of the separator 15 are arranged on one curved portion 12 b of the electrode assembly 12. Therefore, waste of the electrode (positive electrode 13 or negative electrode 14) or separator 15 can be eliminated, and the material cost can be reduced.

  (2) The separator 15 is wound more than one round than the negative electrode 14. Therefore, regardless of the material and thickness of the separator 15, the negative electrode 14 is prevented from being scratched or wrinkled, and the cycle characteristics due to the negative electrode 14 are prevented from being deteriorated.

  (3) The electrode assembly 12 is housed in the case 11 with the top portion 12t of one curved portion 12b in contact with the inner surface of the case 11, and the terminal end 15a of the separator 15 is the terminal end 13c of the positive electrode 13 and the negative electrode 14. , 14 c and in the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15, the top portion 12 t is disposed at the front side position. For this reason, when the electrode assembly 12 is expanded, the winding deviation of the separator 15, the positive electrode 13, and the negative electrode 14 is prevented.

  (4) The terminal end 15a of the separator 15 is such that the circumferential distance L1 between the welding range 23 of the positive electrode 13, the positive electrode conductive member 19 and the negative electrode 14, the negative electrode conductive member 20, and the terminal end 15a of the separator 15 is It arrange | positions in the location which becomes more than the distance of the welding location 19a and the positive electrode active material layer 13a with the electrically conductive member 19, and the distance of the welding location 20a of the negative electrode 14 and the negative electrode conductive member 20, and the negative electrode active material layer 14a. According to this configuration, the heat radiation proceeds until the heat generated at the welding locations 19a and 20a is transmitted to the terminal end 15a of the separator 15 through the metal foil 16 constituting the positive electrode 13 or the negative electrode 14, and the heat during welding is increased. The deformation of the separator 15 due to is prevented.

(5) When the curvature radius of the surface of the curved portion 12b of the electrode assembly 12 is r, the terminal end 15a of the separator 15 includes a case body 11a of the case 11 and a lid body 11b that covers the opening of the case body 11a. It arrange | positions in the position away from the welding location the distance of (2 ^<1/2 > -1) r or more. Therefore, when the case main body 11a and the lid 11b are welded, deformation due to heat generated at the welded portion is prevented. Further, even when welding is performed by ultrasonic welding, it is possible to suppress the slack of the separator 15 due to vibration during welding.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The electrode assembly 12 only needs to have the positive electrode 13, the negative electrode 14, and the terminal ends 13 c, 14 c, 15 a of the separator 15 disposed on one curved portion 12 b of the electrode assembly 12. There is no need to be.

  ○ Instead of the configuration in which the two separators 15 are wound more than one round from the terminal ends 13c, 14c of the positive electrode 13 and the negative electrode 14, one of the two separators 15 is extended by one or more rounds. Thus, the end 15a of the extended separator 15 may be disposed on the curved portion 12b where the end 15a of the separator 15 that does not extend is located. Moreover, when extending the two separators 15, you may make it the frequency | count of winding of the extension part of both the separators 15 differ.

  The electrode assembly 12 does not necessarily have to be disposed at a position where the end 15a of the separator 15 exceeds the ends 13c, 14c of the positive electrode 13 and the negative electrode 14 and exceeds the top 12t. For example, only the terminal end 15a of the separator 15 is disposed at a position corresponding to or exceeding the top 12t of the curved portion 12b, and the terminal ends 13c and 14c of the positive electrode 13 and the negative electrode 14 are both the top of the curved portion 12b. It may be arranged on the rear side in the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15 from 12t.

  ○ In the electrode assembly 12, the positive electrode 13, the negative electrode 14, and the terminal ends 13c, 14c, 15a of the separator 15 are all located after the top portion 12t of the curved portion 12b in the winding direction of the positive electrode 13, the negative electrode 14, and the separator 15. It may be arranged on the side.

  In the electrode assembly 12, the positive electrode 13, the negative electrode 14, and the terminal ends 13c, 14c, and 15a of the separator 15 may be arranged at positions corresponding to the top portion 12t of the curved portion 12b.

  The positive electrode 13 and the negative electrode 14 constituting the electrode assembly 12 are not necessarily limited to the configuration in which the positive electrode active material layer 13a and the negative electrode active material layer 14a are formed on both surfaces of the metal foil 16, but the positive electrode active material on one side of the metal foil 16 The structure in which the material layer 13a and the negative electrode active material layer 14a were formed may be sufficient.

  The electrode assembly 12 is not limited to the configuration in which the negative electrode 14 is disposed outside the positive electrode 13 except for the innermost peripheral portion, and may be configured such that the positive electrode 13 is disposed outside the negative electrode 14. In this case, in the configuration in which the positive electrode active material layer 13 a and the negative electrode active material layer 14 a are formed on both surfaces of the metal foil 16 as the positive electrode 13 and the negative electrode 14, The positive electrode active material layer 13a is formed only on the inner surface side.

  In the secondary battery 10 in which the positive electrode terminal 17 and the negative electrode terminal 18 are fixed to the lid 11b, the electrode assembly 12 includes a curved portion 12b in which the positive electrode 13, the negative electrode 14, and the terminal ends 13c, 14c, and 15a of the separator 15 are disposed. May be arranged on the side facing the lid 11b.

  The step of electrically connecting the electrode assembly 12 to the positive electrode terminal 17 and the negative electrode terminal 18 via the positive electrode conductive member 19 and the negative electrode conductive member 20 is as follows. It is not restricted to the method of welding with the member 20. For example, as shown in FIG. 6, after the positive electrode conductive member 19 and the active material uncoated portion 13b are welded and the negative electrode conductive member 20 and the active material uncoated portion 14b are welded, the positive electrode terminal 17 and The positive electrode conductive member 19, the negative electrode terminal 18 and the negative electrode conductive member 20 may be welded.

  The secondary battery 10 may have a configuration in which the electrode assembly 12 is accommodated in the case 11 with the winding axis direction of the electrode assembly 12 extending in a direction perpendicular to the bottom wall of the case 11. For example, as shown in FIGS. 7A and 7B, in the electrode assembly 12, the active material uncoated portion 13b of the positive electrode 13 faces the lid 11b, and the active material uncoated portion 14b of the negative electrode 14 is present. Is accommodated in the case 11 in a state of facing the bottom wall of the case body 11a, and the positive terminal 17 and the negative terminal 18 may be disposed at two corners facing each other on the diagonal line of the lid 11b. The positive electrode conductive member 19 is provided with a welded portion 19a on the tip side of a portion extending along the upper end of the active material uncoated portion 13b. The negative electrode terminal 18 includes a cylindrical portion 18c extending to the vicinity of the bottom wall of the case body 11a, and the negative electrode conductive member 20 is provided at the lower end of the cylindrical portion 18c in a state extending along the lower end of the active material uncoated portion 14b. A welding point 20a is provided on the tip side. In FIG. 7B, the positive electrode 13, the negative electrode 14, and the separator 15 constituting the electrode assembly 12 are not illustrated individually, but are illustrated as one strip-shaped laminate.

The electrode assembly 12 includes a separator 15 in the secondary battery 10 in which the curved portion 12b in which the positive electrode 13, the negative electrode 14, and the terminal ends 13c, 14c, and 15a of the separator 15 are disposed is opposed to the lid body 11b. When the radius of curvature of the surface of the curved portion 12b of the electrode assembly 12 is r, the terminal end 15a of the electrode assembly 12 is separated by a distance of (2 ^1/2 -1) r or more from the welded portion of the case body 11a and the lid body 11b. What is necessary is just to be arrange | positioned in the position. That is, the minimum distance at which the end 15a of the separator 15 is separated from the welded portion between the case body 11a and the lid 11b is (2 ^1/2 −1) r.

(Circle) the terminal end 15a of the separator 15 may be arrange | positioned in the position away from the welding location of the case main body 11a and the cover body 11b more than the curvature radius of the surface of the curved part 12b of the electrode assembly 12. In this case, the distance at which the terminal end 15a of the separator 15 is separated from the welded portion between the case main body 11a and the lid 11b is larger than in the case of (2 ^1/2 −1) r, and the influence of heat generated at the welded portion is affected. More difficult to receive.

  A case 11 that accommodates the electrode assembly 12 is a lid that covers the opening of the case main body 11a, with the bottom being open and the holes through which the electrode terminals (the positive terminal 17 and the negative terminal 18) protrude are formed in the upper wall. 11b may constitute the bottom wall of the case 11. In this case, the electrode assembly ASSY to which the positive electrode terminal 17, the positive electrode conductive member 19, the negative electrode terminal 18, and the negative electrode conductive member 20 are attached is inserted into the case body from the bottom side of the case 11. 18 is fastened and fixed to the upper wall with a nut 21. Thereafter, the case body and the lid are welded.

  The positive electrode conductive member 19 and the negative electrode conductive member 20 are welded in a state where they are in contact with the active material uncoated portions 13b and 14b from the outer surface side of the wound portion or inserted in an intermediate position of the wound portion. It is good also as a structure welded in the state inserted not only into the structure but the center side of the winding part.

  The positive electrode 13 and the negative electrode 14 are not limited to the configuration in which the active material uncoated portions 13b and 14b are formed over the entire circumference of the electrode assembly 12, but are configured as part of the electrode assembly 12 as so-called tabs. There may be.

  The case 11 that accommodates the electrode assembly 12 is configured such that an opening is formed at a location facing the curved portion 12b of the electrode assembly 12 or a location facing the end of the electrode assembly 12 in the winding axis direction. The configuration is not limited to this, and an opening may be formed at a location facing one of the straight portions 12a of the electrode assembly 12. In this case, after the electrode assembly 12 is accommodated in the case body, the lid body and the case body are welded in a state where the linear portion 12a of the electrode assembly 12 is pressed by the lid body. Therefore, unlike the case where the electrode assembly 12 is inserted into the case body 11a in a state in which the linear portion 12a of the electrode assembly 12 is in contact with the inner surface of the case body 11a, the electrode assembly 12 is accommodated in the middle of housing the electrode assembly 12 in the case body 11a. A large force is not applied to the solid 12.

  The case 11 is not limited to a rectangular box-shaped square, and may have a structure having a constraining surface that constrains the straight portion 12a of the electrode assembly 12, for example, a wall surface of a portion corresponding to the curved portion 12b. The shape formed by a curved surface, or the shape where the wall of the part corresponding to the curved part 12b was bent in two may be sufficient.

The secondary battery 10 is not limited to a lithium ion secondary battery, and may be another secondary battery such as a nickel hydrogen secondary battery or a nickel cadmium secondary battery.
The power storage device is not limited to the secondary battery 10 and may be a capacitor such as an electric double layer capacitor or a lithium ion capacitor.

  L1, L2 ... Distance, 10 ... Secondary battery as power storage device, 12 ... Electrode assembly, 11 ... Case, 11a ... Case body, 11b ... Lid, 12b ... Curved part, 12t ... Top part, 13 ... Positive electrode, 13c , 14c, 15a ... terminal, 14 ... negative electrode, 15 ... separator, 19 ... positive electrode conductive member, 19a, 20a ... welding location, 20 ... negative electrode conductive member, 23 ... welding range.

Claims (6)

A flat electrode assembly wound with a strip-shaped separator interposed between a strip-shaped positive electrode and a strip-shaped negative electrode is a power storage device housed in a case,
The power storage device, wherein terminal ends of the positive electrode, the negative electrode, and the separator are arranged on one curved portion of the electrode assembly.   The power storage device according to claim 1, wherein the separator is wound more than one round than the positive electrode and the negative electrode.   The electrode assembly is accommodated in the case in a state in which the top of the one curved portion is in contact with the inner surface of the case, and the end of the separator exceeds the end of the positive electrode and the negative electrode, and the positive electrode 3. The power storage device according to claim 1, wherein the power storage device is disposed at a position in front of the top in the winding direction of the negative electrode and the separator.   The end of the separator is determined by the distance between the welding range of the positive electrode and the positive electrode conductive member, the negative electrode and the negative electrode conductive member, and the end of the separator in the winding circumferential direction. The power storage device according to any one of claims 1 to 3, wherein the power storage device is disposed at a location that is equal to or greater than a distance from the material layer and a distance between a weld location between the negative electrode and the negative electrode conductive member and the active material layer. . When the radius of curvature of the surface of the curved portion of the electrode assembly is r, the end of the separator is (2 ¹⁾ from the welded portion between the case main body of the case and the lid that covers the opening of the case main body. ^/ 2-1) The power storage device according to any one of claims 1 to 4, which is disposed at a position separated by a distance equal to or greater than r.   The end of the separator is disposed at a position that is a distance greater than or equal to the radius of curvature of the surface of the curved portion of the electrode assembly from the weld location between the case main body of the case and the lid that covers the opening of the case main body. The electrical storage apparatus as described in any one of Claims 1-4.