JP6318887B2 - Electricity storage element - Google Patents

Description

  The present invention relates to a battery including a nonaqueous electrolyte secondary battery and a power storage element such as a capacitor.

  A battery including a non-aqueous electrolyte secondary battery and an electrode body included in a power storage element such as a capacitor have a structure in which a belt-like positive electrode sheet, a negative electrode sheet, and two separators are overlapped and wound. is there. Active material layers are provided on both surfaces of the positive electrode sheet and the negative electrode sheet, and leads that expose the metal foil without forming the active material layer are provided at one end in the width direction. A separator is interposed between the positive electrode sheet and the negative electrode sheet. The lead protrudes from either one of both ends in the width direction of the separator.

  The electrode body included in the secondary battery disclosed in Patent Document 1 includes a joining portion in which two separators are joined by thermal welding at one end in the width direction opposite to the lead of the positive electrode sheet and / or the negative electrode sheet. . By providing the joining portion, one end of the positive electrode sheet and / or the negative electrode sheet opposite to the lead is wrapped with two separators, and foreign matter contact with this portion is prevented. The foreign material includes, for example, a metal piece generated when the positive electrode sheet and / or the negative electrode sheet lead is ultrasonically welded to the current collector.

JP2011-216399A

  By the way, in the curved portion of the above-described wound electrode body, the curvature and the circumferential length of each layer become larger toward the outer side. Therefore, when the positive electrode sheet, the negative electrode sheet, and the two separators are overlapped and wound, the inner layer having a small peripheral length is likely to be distorted. In order to suppress the occurrence of such distortion, winding may be performed while the inner layer is appropriately displaced in the length direction by the same distance as the difference in circumference with respect to the outer layer.

  However, when two separators are joined as in the technique of Patent Document 1, it is difficult to suppress distortion because the inner separator cannot be displaced in the length direction with respect to the outer separator. Therefore, wrinkles are likely to occur in each layer of the electrode body, and depending on the level of wrinkles, it may become impossible to wind to the end.

  Then, this invention makes it a subject to suppress generation | occurrence | production of the wrinkle in each layer which comprises an electrode body, preventing the contact of the foreign material to the positive electrode sheet and / or negative electrode sheet with which the electrode body of an electrical storage element is equipped.

In the present invention, the positive electrode sheet, the negative electrode sheet, and the first and second separators are overlapped with each other such that the first or second separator is interposed between the positive electrode sheet and the negative electrode sheet. an electrode body formed by winding from the direction of one end side, the electrode body provides a power storage device having a junction formed by joining some of the other longitudinal end side of the front Symbol first and second separators .

  In addition, said 1st and 2nd separator may be isolate | separated from each other and may be connected. As an example, one of the two sheets may constitute the first separator, and the other sheet may constitute the second separator. As another example, among a plurality of layers formed by folding one sheet, the first separator may be configured with a predetermined layer, and the second separator may be configured with another layer.

In the electricity storage device according to a specific aspect, the joining portion includes a length portion exceeding one turn wound on the outermost side of at least one of the positive electrode sheet and the negative electrode sheet. provided to wrap in the separator are wound. Thereby, it can control reliably by the junction part of a 1st and 2nd separator that a foreign material contacts at least 1 round arrange | positioned at the outermost radial direction of a positive electrode sheet and / or a negative electrode sheet. Examples of the foreign material include a metal piece generated when the positive electrode sheet and / or the negative electrode sheet is ultrasonically welded to the current collector.

  In the electrical storage element according to another specific aspect, the joining portion includes a length portion of at least one of the positive electrode sheet and the negative electrode sheet that is not longer than half of the other end side in the longitudinal direction. It is provided to be wrapped with a separator. Thereby, at the time of manufacture, until the half of the longitudinal direction of a positive electrode sheet and / or a negative electrode sheet is wound, the junction part of the 1st and 2nd separator is not wound, thereby Distortion can be prevented. Moreover, when the joining part of the first and second separators starts to be wound, winding of the positive electrode sheet and / or the negative electrode sheet in the longitudinal direction is more than half, and the circumferential length for one round is sufficient. It is getting bigger. At this time, the difference in circumferential length between the inner separator and the outer separator is sufficiently smaller than the circumferential length of one round of the separator, and the separator is unlikely to be distorted. It is possible to wind well until the end while preventing the occurrence.

  In the case where the first and second separators each include an extension portion that extends to the other end side in the longitudinal direction from the positive electrode sheet and the negative electrode sheet, the joint portion is provided to extend together with the extension portion. May be. Thereby, it can suppress that the 1st and 2nd separator which comprises the outer peripheral part of an electrode body mutually shifts.

  According to the present invention, the portion of the total length of the positive electrode sheet and / or the negative electrode sheet that is wound on the outer side in the radial direction of the electrode body, in which foreign matter is relatively easy to enter, is the first and second separators joined together. When the part is wound around the inner side in the radial direction where the foreign object is prevented from coming into contact and the foreign object is unlikely to enter, the first and second separators are not joined, so that the part is wound. Relative movement between the separators is allowed, and the distortion of the separators can be prevented. In addition, when winding the radially outer portion, the circumference for one round becomes large, and the influence due to the difference in circumference between the inner separator and the outer separator becomes small. Distortion is unlikely to occur. Therefore, at the time of manufacturing the electrode body, it is possible to wind well until the end while preventing generation of wrinkles of each layer constituting the electrode body.

1 is an exploded perspective view of a nonaqueous electrolyte secondary battery according to a first embodiment of the present invention. The perspective view of the electrode body with which the battery shown in FIG. 1 is provided. The front view which shows the edge part by the side of the negative electrode of the battery shown in FIG. 1 (III arrow directional view of FIG. 1). FIG. 4 is a schematic sectional view of the electrode body shown in FIG. 2 (a sectional view taken along line IV-IV in FIG. 1). The schematic diagram which shows the length range of the junction part of the electrode body shown in FIG. The schematic diagram of the manufacturing apparatus of the electrode body shown in FIG. The typical perspective view of the welding part of the manufacturing apparatus shown in FIG. Sectional drawing similar to FIG. 4 which shows the electrode body with which the nonaqueous electrolyte secondary battery which concerns on 2nd Embodiment of this invention is provided. Sectional drawing similar to FIG. 4 which shows the electrode body with which the nonaqueous electrolyte secondary battery which concerns on 3rd Embodiment of this invention is provided.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

[First Embodiment]
FIG. 1 shows a nonaqueous electrolyte secondary battery (hereinafter simply referred to as “battery”) 1 according to a first embodiment of the present invention. The battery 1 includes a casing 4 composed of a container 2 whose upper end is opened and a lid 3 that closes the opening of the container 2. An electrode body 5 is accommodated in the casing 4. Further, in the casing 4, an electrolytic solution (not shown) injected through a liquid injection port 3 a formed in the lid 3 is accommodated.

  2 and 3, the electrode body 5 includes positive and negative electrode leads 17 and 23, which will be described in detail later. These leads 17 and 23 are legs of the positive and negative current collectors 6A and 6B, respectively. It is electrically connected to the part 6a. The positive and negative current collectors 6A and 6B are electrically connected to the positive and negative external terminals 7A and 7B, respectively. The external terminals 7A and 7B have, for example, a bolt-shaped connection portion 7a that protrudes from the lid 3 to the outside. However, the external terminals 7A and 7B may include a plate-like connection portion instead of the bolt-like connection portion 7a. A lower packing 8 is interposed between the current collectors 6 A and 6 B and the lower surface of the lid 3, and an upper packing 9 is interposed between the external terminals 7 A and 7 B and the upper surface of the lid 3.

  The electrode body 5 is formed by laminating a positive electrode sheet 11, a negative electrode sheet 12, a first separator 13, and a second separator 14 (see FIG. 2) each having a long strip shape with a constant width, and one end side in the longitudinal direction thereof. It is a wound body formed by winding from. The electrode body 5 is formed in an elliptic cylinder shape with a high flatness having a pair of curved portions 5a and 5b. One of the first and second separators 13 and 14 is interposed between one layer of the positive electrode sheet 11 and one layer of the negative electrode sheet 12 adjacent thereto. The electrode body 5 is accommodated in the casing 4 in such a posture that one curved portion 5a constitutes the upper end portion and the other curved portion 5b constitutes the lower end portion.

  FIG. 4 schematically shows a cross-sectional view taken along line IV-IV in FIG. In FIG. 4, a part of the layer outside the electrode body 5 in the radial direction (the direction of arrow D in FIG. 4) is illustrated, and the remaining layers are not illustrated. The layer 14 illustrated on the lowermost side in FIG. 4 is the outermost layer of the electrode body 5.

  As shown in FIG. 4, the positive electrode sheet 11 includes a strip-shaped positive metal foil 15 and a positive electrode active material layer 16 formed on both surfaces of the positive metal foil 15. At one end portion 11a in the width direction of the positive electrode sheet 11 (right side in FIG. 4), the positive electrode active material layer 16 is provided up to the edge portion 11c. A positive electrode lead 17 in which the positive electrode metal foil 15 is exposed without providing the positive electrode active material layer 16 is provided at the other end portion 11 b in the width direction of the positive electrode sheet 11 (left side in FIG. 4).

  The negative electrode sheet 12 includes a strip-shaped negative electrode metal foil 21 and a negative electrode active material layer 22 formed on both surfaces of the negative electrode metal foil 21. At one end 12b in the width direction of the negative electrode sheet 12 (left side in FIG. 4), the negative electrode active material layer 22 is provided up to the edge 12c, but the other in the width direction of the negative electrode sheet 12 (right side in FIG. 4). The end portion 12 a is provided with a negative electrode lead 23 in which the negative electrode metal foil 21 is exposed without providing the negative electrode active material layer 22.

  As shown in FIGS. 1 and 3, the positive electrode lead 17 and the negative electrode lead 23 protruding from the separators 13 and 14 are connected to the leg portions 6 a of the current collectors 6 A and 6 B through clips 24. For example, the leads 17 and 23 and the clip 24 are ultrasonically welded, and the clip 24 and the leg portions 6a of the current collectors 6A and 6B are ultrasonically welded.

  The first and second separators 13 and 14 are composed of separate sheets. However, two layers are formed by folding one belt-like sheet along a fold extending in the lateral direction, and the first separator 13 is formed by one layer, and the second separator 14 is formed by the other layer. May be configured. The separators 13 and 14 are made of a microporous resin sheet. The lengths of the separators 13 and 14 are larger than the lengths of the positive electrode sheet 11 and the negative electrode sheet 12. Therefore, as shown in FIG. 4, some of the outermost layers of the electrode body 5 are composed of only the first and second separators 13 and 14. The first and second separators 13 and 14 are arranged such that the position of one end portion 13a and 14a in the width direction (the right side in FIG. 4) and the other end portion 13b and 14b (the left side in FIG. 4) are positioned. Both are available.

  The positive electrode sheet 11 and the negative electrode sheet 12 are separated from each other so that the positive electrode lead 17 and the negative electrode lead 23 protrude from one of the end portions 13a, 13b, 14a, 14b in the width direction of the first and second separators 13, 14. , 14 is shifted in the width direction. For the positive electrode sheet 11, the end portion 11 b provided with the positive electrode lead 17 protrudes from the left end portions 13 b and 14 b of the separators 13 and 14 in FIG. 4, and the end portion 11 a opposite to the positive electrode lead 17 14 is located on the inner side in the width direction from the right end portions 13a, 14a in FIG. With respect to the negative electrode sheet 12, the end portion 12 a provided with the negative electrode lead 23 protrudes from the right end portions 13 a and 14 a of the separators 13 and 14 in FIG. 4, and the end portion 12 b on the opposite side of the negative electrode lead 23 is the separators 13 and 14. 4 is located on the inner side in the width direction than the left end portions 13b and 14b in FIG.

  A part of the outer side of the electrode body 5 in the radial direction is provided with a joint part 26 in which one end (a right side in FIG. 4) of the first and second separators 13 and 14 is joined to each other. . However, the joint portion 26 may be provided on the inner side in the width direction than the tips of the end portions 13a and 14a. In this case, the end portions 13a and 14a are disposed on the outer side in the width direction with respect to the first and second ends. 2 is provided with a separation part to which the two separators 13 and 14 are not joined.

  The joint portion 26 is provided continuously with a substantially constant width W1 (see FIG. 7) in the winding direction of the positive electrode sheet 11, the negative electrode sheet 12, and the separators 13 and 14 (longitudinal direction of the separators 13 and 14). In the present embodiment, the joining portion 26 is formed by ultrasonic welding of the first and second separators 13 and 14. However, the method for forming the joint portion 26 is not limited, and for example, the joint portion 26 may be formed by heat fusion or mechanical pressure bonding. In the layer provided with the joint portion 26, the end portion 11 a (the end portion on the side opposite to the positive electrode lead 17) of the positive electrode sheet 11 is wrapped with the first and second separators 13 and 14.

  By wrapping the end portion 11a of the positive electrode sheet 11 with the first and second separators 13 and 14, contact of foreign matters to this portion is prevented. Examples of the foreign material include a metal piece generated in the welded portion 10 when the negative electrode lead 23 of the negative electrode sheet 12 is ultrasonically welded to the clip 24. When the positive electrode metal foil 15 of the positive electrode sheet 11 is made of aluminum and the negative electrode metal foil 21 of the negative electrode sheet 12 is made of copper, when the negative electrode lead 23 of the negative electrode sheet 12, that is, the negative electrode metal foil 21 is ultrasonically welded to the clip 24. A copper piece is generated. If the copper piece comes into contact with the positive electrode sheet 11, the copper piece is dissolved electrochemically, and when the copper that has become ions reaches the negative electrode sheet 12, copper is deposited on the negative electrode sheet 12. When the deposited copper breaks through the separators 13 and 14 and energizes the positive electrode, a minute current flows and the voltage of the battery 1 decreases. According to the present embodiment, by providing the joint portion 26 of the separators 13 and 14 and covering the positive electrode sheet 11 including the positive electrode metal foil 15 made of, for example, aluminum, for example, the copper piece comes into contact with the positive electrode sheet 11 and is electrochemical. It can be prevented from dissolving in.

  FIG. 5 is a perspective view showing a part in the longitudinal direction of the first and second separators 13 and 14 and the positive electrode sheet 11, specifically, a length portion forming some outermost layers of the electrode body 5. FIG. Hereinafter, the longitudinal ends of the separators 13 and 14 disposed in the outermost layer of the electrode body 5 are referred to as the tips 13c and 14c of the separators 13 and 14, respectively.

  As shown in FIG. 5, the separators 13 and 14 include extension portions 43 and 44 that extend toward the distal ends 13 c and 14 c in the longitudinal direction from the positive electrode sheet 11. When the lengths of the first and second separators 13 and 14 before winding are the same, and the first separator 13 is wound inside the second separator 14, the winding is performed for reasons described later. As the rotation proceeds, the unwinding portion of the first separator 13 becomes longer than the unwinding portion of the second separator 14. Therefore, the extension 43 of the first separator 13 is longer than the extension 44 of the second separator 14.

  The joint portion 26 is formed by joining a part of the first and second separators 13 and 14 on the side of the distal ends 13c and 14c in the longitudinal direction. The joint portion 26 includes an envelope portion 26 a having a length overlapping with the positive electrode sheet 11, and an extension portion 26 b that is extended to the distal ends 13 c and 14 c side of the positive electrode sheet 11 together with the separators 13 and 14.

  In the envelope part 26 a, the positive electrode sheet 11 is wrapped with the first and second separators 13 and 14, so that the contact of foreign matter with the positive electrode sheet 11 is reliably regulated. Since the gap between the layers in the radially outer portion of the electrode body 5 is easier to expand than in the inner portion, foreign matter is likely to enter. According to the present embodiment, the positive electrode sheet 11 is effectively wrapped in the first and second separators 13 and 14 at the portion that is wound outward in the radial direction in which foreign matter is likely to enter, so that contact with the foreign matter is effective. Regulated by

  If the length L of the envelope portion 26a is too small, the positive electrode sheet 11 cannot be effectively protected from contact with foreign matter. Therefore, it is preferable that the length L of the envelope portion 26a is larger than the length L1 of one turn wound around the outermost side of the positive electrode sheet 11. Thus, at least one outermost layer of the positive electrode sheet 11 is wrapped with the first and second separators 13 and 14 and is reliably protected from contact with foreign matter.

  If the length L of the envelope portion 26a is too large, the separators 13 and 14 are likely to be distorted during winding as will be described in detail later. The length L of the envelope portion 26 a is preferably less than or equal to half the length of the positive electrode sheet 11. In this case, the length portion of the positive electrode sheet 11 wrapped by the first and second separators 13 and 14 is a length portion that is not more than half of the outer side in the radial direction, and the joint portion 26 is attached to the remaining length portion. Is not formed. In the length portion where the joint portion 26 is not formed, the movement of each layer of the separators 13 and 14 is not restricted by another layer of the separators 13 and 14. Therefore, as described in detail later, when winding the length portion where the joint portion 26 is not formed, the first separator 13 is appropriately displaced in the longitudinal direction with respect to the second separator 14, thereby separating the separators 13, 14. It is possible to prevent distortion from occurring. In addition, in the length portion where the joint portion 26 is not formed, the electrolyte can freely pass between the layers of the separators 13 and 14, so that rapid liquid injection is possible.

  Thus, the length L of the envelope portion 26a is determined to be a length that can effectively protect the positive electrode sheet 11 from foreign substances while suppressing the distortion of the separators 13 and 14 during winding. Specifically, the length L of the envelope portion 26a may be a length corresponding to a plurality of turns wound around the outermost side of the positive electrode sheet 11, for example, a length corresponding to two or three turns.

  The extension part 26 b extends to the tip 14 c of the second separator 14 that is shorter than the first separator 13. By providing the extension part 26b, it is possible to prevent the first and second separators 13 and 14 constituting the outer peripheral part of the electrode body 5 from being displaced from each other.

  FIG. 6 is a conceptual schematic diagram of the manufacturing apparatus 30 for the electrode body 5. The manufacturing apparatus 30 includes a supply bobbin 31 in which the positive electrode sheet 11 is wound in a coil shape, a supply bobbin 32 in which the negative electrode sheet 12 is wound in a coil shape, and a supply bobbin 33 in which the first separator 13 is wound in a coil shape. And a supply bobbin 34 around which the second separator 14 is wound in a coil shape. The positive electrode sheet 11, the negative electrode sheet 12, the first separator 13, and the second separator 14 that are unwound from the supply bobbins 31 to 34 are wound around the rotating winding frame 35 in a state where they are overlapped with each other. By being wound around the winding frame 35, an elliptical cylindrical electrode body 5 in which the stacked positive electrode sheet 11, negative electrode sheet 12, first separator 13 and second separator 14 are wound many times is obtained.

  The manufacturing apparatus 30 includes a welded portion 36 that welds the end portions 13 a and 14 a of the first and second separators 13 and 14 to form the joint portion 26. Further, in the direction in which the positive electrode sheet 11, the first separator 13, and the second separator 14 are fed toward the winding frame 35 (in the direction of arrow A in FIG. 7), the upstream side and the downstream side across the welding portion 36 are A pair of guide rollers 39a, 39b, 40a, 40b is provided.

  Referring also to FIG. 7, in the welding portion 36, the first and second separators 13 and 14 unwound from the supply bobbins 33 and 34 are overlapped, and the positive electrode unwound from the supply bobbin 31 therebetween. A sheet 11 is disposed. The end portion 11 b on the positive electrode lead 17 side of the positive electrode sheet 11 protrudes from the end portions 13 b and 14 b of the separators 13 and 14. On the other hand, the end portion 11a of the positive electrode sheet 11 opposite to the positive electrode lead 17 is located on the inner side in the width direction than the end portions 13a and 14a of the separators 13 and 14. At this time, the separators 13 and 14 and the positive electrode sheet 11 are sandwiched between a pair of guide rollers 39a, 39b, 40a, and 40b (see FIG. 6) on the upstream side and the downstream side of the welding portion 36, respectively.

  The welding portion 36 includes a horn 37A that vibrates ultrasonically by the operation of an ultrasonic transmitter (not shown), and an anvil 37B that faces the tip of the horn 37A. The horn 37A is provided so as to be able to approach and leave the anvil 37B. The anvil 37B is disposed at a position where the separators 13 and 14 can be supported from below by the end portions 13a and 14a. The anvil 37B is composed of, for example, a rotatable roller.

  Further, the welding portion 36 includes a pair of feed rollers 38A and 38B (see FIG. 7) that sandwich the separators 13 and 14 and the positive electrode sheet 11 in the vicinity of the end portions 13a and 14a. The pair of feed rollers 38 </ b> A and 38 </ b> B and the roller-shaped anvil 37 </ b> B rotate in the direction of feeding the separators 13 and 14 and the positive electrode sheet 11 toward the winding frame 35.

  When the horn 37A ultrasonically vibrates with the horn 37A and the anvil 37B sandwiching the end portions 13a, 14a of the first and second separators 13, 14, the end portions 13a, 14a are ultrasonically welded to each other, and the width W1 The joint portion 26 is formed. When the end portions 13a and 14a of the separators 13 and 14 pass between the horn 37A and the anvil 37B in a state where the horn 37A is separated from the anvil 37B, the joint portion 26 is not formed at the passing portion. In the welded portion 36, the joint portion 26 can be formed only at a desired position in the longitudinal direction of the separators 13 and 14 by controlling the operation of the horn 37A.

  The negative electrode sheet 12 unwound from the supply bobbin 32 is superposed on the separators 13 and 14 and the positive electrode sheet 11 that have passed through the welding portion 36, and is wound up by the winding frame 35. At this time, in the curved portions forming the curved portions 5a and 5b (see FIG. 2) of the electrode body 5, the curvature and circumferential length of the outer layer are longer than those of the inner layer. When the curved portion is formed by winding with the winding frame 35, the unwinding of the positive electrode sheet 11, the negative electrode sheet 12, and the separators 13 and 14 from the supply bobbins 31 to 34 is performed on the inner layer with respect to the outer layer. This is performed while appropriately displacing in the direction opposite to the feeding direction (the direction of arrow A in FIG. 7) by the same distance as the difference in the peripheral length of the curved portion, thereby causing the positive electrode sheet 11 and the negative electrode sheet due to the difference in peripheral length. 12 or the separators 13 and 14 can be prevented from being distorted.

  Until the middle of the manufacturing process described above, the joint portion 26 is not formed on the first and second separators 13 and 14 by the weld portion 36. When winding the length portion where the joint portion 26 is not formed, the inner separator 13 is displaced toward the distal end 13c in the longitudinal direction with respect to the outer separator 14, and the separators 13 and 14 caused by the difference in circumferential length are displaced. The strain can be extended. When the length portion including the joining portion 26 of the first and second separators 13 and 14 starts to be wound, the winding of the length portion more than half of the positive electrode sheet 11 is completed, and one turn The perimeter is sufficiently large. At this time, the difference in circumferential length between the inner separator 13 and the outer separator 14 is sufficiently smaller than the circumferential length of one round of the separators 13 and 14, and the distortion of the separators 13 and 14 due to the circumferential length difference is small. Not likely to occur. Therefore, winding of the positive electrode sheet 11, the negative electrode sheet 12, and the separators 13 and 14 by the winding frame 35 can be satisfactorily performed to the end while preventing generation of wrinkles in each layer.

  As described above, the joint portion 26 can be formed by heat fusion or pressure bonding instead of ultrasonic welding. In the case of forming the joint portion 26 by thermal fusion, a pair of heat rollers that sandwich the end portions 13a and 14a of the separators 13 and 14 may be disposed instead of the horn 37A and the anvil 37B in FIGS. In this case, the end portions 13a and 14a of the separators 13 and 14 are heat-sealed to each other by heating and pressurization with a pair of heat rollers. When forming the joint portion 26 by pressure bonding, a pair of pressure rollers, for example, mechanical gears, may be disposed instead of the horn 37A and the anvil 37B in FIGS. In this case, the end portions 13a and 14a of the separators 13 and 14 are pressure-bonded to each other by pressure applied by the pressure-bonding roller. In the case of arranging a pair of heat rollers or a pair of pressure rollers, the non-bonding region 29 can be formed by providing a retracting mechanism for separating the pair of heat rollers or the pair of pressure rollers from each other. The joint portion 26 can also be formed by a double-sided tape or a paste.

[Second Embodiment]
FIG. 8 shows an electrode body 5 provided in a battery according to the second embodiment of the present invention. The overall structure of the battery of this embodiment is the same as that of the first embodiment (see FIG. 1).

  A protective layer 51 is provided on the end surface 11 c on the end 11 a side of the positive electrode sheet 11. In the present embodiment, the protective layer 51 is made of an insulating material. An example of the insulating material is alumina. For example, the protective layer 51 having insulating properties can be provided by applying alumina paste to the end face 11 c of the positive electrode sheet 11.

  By providing the protective layer 51, even when the separators 13 and 14 are separated at the joint portion 26, it is possible to reliably prevent foreign matter from coming into contact with the end surface 11 c of the positive electrode sheet 11. For example, when the positive electrode metal foil 15 is made of aluminum and the negative electrode metal foil 21 is made of copper, it is particularly effective to provide a protective layer 51 having insulating properties. Specifically, the copper piece generated during the ultrasonic welding of the negative electrode metal foil 21 is a portion where the joining portion 26 is not formed at the end portions 13 a and 14 a of the separators 13 and 14, or the separator 13 of the joining portion 26. , 14 even after passing through the part where the separation has occurred and reaching the end face 11c of the positive electrode sheet 11, the presence of the protective layer 51 does not melt the copper piece and does not cause a short circuit.

[Third Embodiment]
FIG. 9 shows an electrode body 5 provided in a battery according to the third embodiment of the present invention. The overall structure of the battery of this embodiment is the same as that of the first embodiment (see FIG. 1).

  The electrode body 5 of the present embodiment is provided with a joining portion 56 of the separators 13 and 14 so as to wrap the end portion 12b of the negative electrode sheet 12 opposite to the negative electrode lead 23. The joining portion 56 is provided on a part of the separators 13 and 14 in the longitudinal direction so that at least one circumference of the outermost layer of the negative electrode sheet 12 is wrapped by the first and second separators 13 and 14. Thereby, the contact of the foreign material to the end portion 12b of the negative electrode sheet 12 can be effectively prevented in the radially outer portion where the foreign material easily enters. That is, according to the present embodiment, it is possible to effectively prevent foreign matter from contacting both the positive electrode sheet 11 and the negative electrode sheet 12.

  Since the joining portion 56 is partially formed in the length portion of the separators 13 and 14 constituting the outer layer of the electrode body 5, the first and second separators 13 and 14 have a diameter larger than that of the joining portion 56. In the length part which comprises the layer inside a direction, it can move relatively to a longitudinal direction. Therefore, as in the first embodiment, it is possible to perform favorable winding while preventing wrinkles of the separators 13 and 14 and to improve the liquid injection property. A protective layer 51 (see FIG. 8) similar to that in the second embodiment may be provided on both or either one of the end surface 11c of the positive electrode sheet 11 and the end surface 12c of the negative electrode sheet 12.

  While the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment, the power storage device according to the present invention has been described by taking a non-aqueous electrolyte secondary battery as an example. However, the present invention is also applicable to other batteries and capacitors including an electrode body having a similar or similar structure. it can. For example, the present invention can be applied to an electrode body including a positive electrode sheet and a negative electrode sheet in which a plurality of active material layers are provided at intervals in a metal foil. Further, the present invention can also be applied to an electrode body including a positive electrode sheet and a negative electrode sheet in which an active material layer is provided in the entire width direction of the metal foil.

1: Battery (electric storage element)
2: Container 3: Lid 3a: Injection port 4: Casing 5: Electrode 5a, 5b: Curved part 6A, 6B: Current collector 6a: Leg part 7A, 7B: External terminal 8: Lower packing 9: Upper packing DESCRIPTION OF SYMBOLS 10: Welding part 11: Positive electrode sheet 11a, 11b: End part of positive electrode sheet 12: Negative electrode sheet 12a, 12b: End part of negative electrode sheet 13: 1st separator 13a: End part of 1st separator 14: 2nd Separator 14a: End of second separator 15: Positive electrode metal foil 16: Positive electrode active material layer 17: Positive electrode lead 21: Negative electrode metal foil 22: Negative electrode active material layer 23: Negative electrode lead 24: Clip 26: Junction 26a: Envelope Part 26b: Extension part 30: Manufacturing apparatus 31, 32, 33, 34: Supply bobbin 35: Winding frame 36: Welding part 37A: Horn 37B: Anvil 8A, 38B: Feed roller 43: extension 44: extension 51: Protective layer 56: joint

Claims (3)

One end side in the longitudinal direction of the positive electrode sheet, the negative electrode sheet, and the first and second separators are overlapped so that the first or second separator is interposed between the positive electrode sheet and the negative electrode sheet. Comprising an electrode body wound from
The electrode body is Bei give a joint formed by bonding a portion of the other longitudinal end side of the front Symbol first and second separators,
The joint portion is provided and wrapped around the first and second separators so as to wrap a length portion of at least one of the positive electrode sheet and the negative electrode sheet, which is longer than one turn wound on the outermost side. power storage device characterized by being. The joining portion is provided so as to wrap a length portion of at least one of the positive electrode sheet and the negative electrode sheet that is not more than half of the other end side in the longitudinal direction with the first and second separators. The power storage device according to claim 1 . The first and second separators each include an extended portion that extends to the other end side in the longitudinal direction from the positive electrode sheet and the negative electrode sheet,
The junction storage element according to claim 1 or 2, characterized in that it is provided to extend along with the extension.

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