JP2019121427A - Power storage element - Google Patents

Abstract

To provide a power storage element that, even if electrodes expand, hinders concentration of pressure in a layering direction, resulting from the expansion.SOLUTION: A power storage element comprises an electrode body 2 having: a first member including a first electrode 21; and a plurality of second members 26 including a second electrode 22 different from the first electrode 21 in polarity. The first member is sandwiched between the second members 26 adjacent in a first direction. The adjacent second members 26 are identical in dimension in a second direction orthogonal to the first direction. In the second direction, the position of an end edge, in the second direction, of a contact surface of one second member 26 of the adjacent second members 26 with the first member is different from the position of an end edge of a contact surface of the other second member 26 of the adjacent second members 26 with the first member.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a storage element provided with an electrode body having an electrode.

  Conventionally, a lithium ion secondary battery (hereinafter, simply referred to as "battery") in which one of a positive electrode and a negative electrode is folded and laminated in a bellows shape is known (see, for example, Patent Document 1). Specifically, as shown in FIG. 17, this battery includes an electrode assembly 102 formed by combining a negative electrode / separator pressure-bonded body 121 and a positive electrode 122 and folding it in a bellows shape.

  The negative electrode-separator pressure-bonded body 121 is formed by pressure-bonding a strip-like negative electrode body 124 having a negative electrode as a base material between a pair of continuous strip-like separators 123, and is continuous as a whole as a strip. The positive electrode 122 is configured by connecting a plurality of strip-shaped metal foils by a positive electrode lead. The positive electrode 122 faces the negative electrode / separator pressure-bonded body 121 in the thickness direction of the positive electrode 122.

  When manufacturing the said electrode body 102, first, the strip | belt-shaped negative electrode body 124 is arrange | positioned between a strip-like pair of separators 123, and these are crimped | bonded by a press etc., The negative electrode and separator crimp body 121 are formed. Do. Furthermore, after forming a fold in the negative electrode / separator crimped body 121 and inserting the positive electrode 122 into the negative electrode / separator crimped body 121, the electrode assembly 102 is manufactured by folding this along the fold.

  By the way, in the battery provided with the electrode body 102, when the positive electrode 122 or the negative electrode body 124 expands, a pressure resulting from the expansion is applied to the contact surface of the positive electrode 122 with the negative electrode / separator pressure bonding member 121, particularly, the contact There was a risk of concentrating on the edge of the surface.

JP, 2013-222602, A

  So, this embodiment aims at providing the electrical storage element which suppressed concentration of the pressure in the lamination direction resulting from this expansion, even if the 1st electrode and the 2nd electrode expand.

The storage element of the present embodiment is
An electrode body having a first member including a first electrode, and a plurality of second members including a second electrode different in polarity from the first electrode;
The first member is sandwiched between the adjacent second members in a first direction,
The dimensions in the second direction orthogonal to the first direction of the adjacent second members are the same,
The position of the edge of one side in the second direction of the contact surface of the one second member of the adjacent second members with the first member, and the other of the adjacent second members The position of the one end of the contact surface of the second member with the first member is different in the second direction.

  According to this configuration, the position of the edge of the contact surface of the second member with the first member is different, so when using the storage element having the same dimension in the second direction of the second member, the first electrode or Even if the second electrode expands, the pressure in the stacking direction due to the expansion can be prevented from being concentrated at this edge of the second member.

In the storage element,
The edge of the one side of the contact surface of the one second member is located on the other side in the second direction than the edge of the one side of the contact surface of the other second member,
The one second member extends from the edge of the one side of the contact surface of the one second member to the one side, and the distance from an imaginary plane including the contact surface of the one second member Has a first inclined surface inclined so that the one side is larger,
The second electrode extends along the contact surface of the one second member, extends along at least a portion of the first inclined surface, and extends in the entire second direction in the second direction. It may be opposed to one electrode.

  According to this configuration, since the portion of the second electrode extending along the first inclined surface faces the first electrode, the facing area between the second electrode and the first electrode is increased. The energy density of the storage element can be increased.

In the storage element,
The other second member extends from the edge of the one side of the other second member to the one side, and the distance from an imaginary plane including the contact surface of the other second member is the one side Have a second inclined surface inclined so as to be
The second electrode extends along the contact surface of the other second member, extends along at least a portion of the second inclined surface, and extends in the entire second direction in the second direction. It may be opposed to one electrode.

  According to this configuration, the portion extending along the first inclined surface or the second inclined surface of the second electrode faces the first electrode, whereby the second electrode and the first electrode face each other. Since the area is increased, the energy density of the storage element can be increased. In addition, since the position of the edge of the contact surface of the one second member with the first member is different from the position of the edge of the contact surface of the other second member with the first member, the second member When using a storage element having equal dimensions in two directions, even if the first electrode or the second electrode expands, the pressure in the stacking direction resulting from this expansion is concentrated at this edge of the second member Can be suppressed.

In the storage element,
An electrolytic solution,
And a case for containing the electrode body and the electrolytic solution,
The first member has a folded back portion turned at a turn portion so as to open the other side,
The one second member is sandwiched by the folded portion,
The end of the one side of the one second member is disposed inside the turn portion,
The other end of the one second member is disposed on the other side of the folded portion,
The one second member extends from the other side edge of the one second member to the other side, and the distance from the virtual surface including the contact surface of the other second member is the other side Have a third inclined surface inclined so as to be
The inclination of the first inclined surface with respect to the virtual surface including the contact surface of the one second member is the inclination of the third inclined surface with respect to the virtual surface including the contact surface of the one second member It may be more gradual.

  According to this configuration, on the one side in the second direction, the end of one side of the second member has the first inclined surface, so that the end of the turn does not have the inclined surface. The inner region becomes wider, and the electrolyte is likely to flow from the outside into the inner region of the turn. Thereby, in such a configuration, the supply amount of the electrolytic solution to the inside of the turn portion is increased. Moreover, on the other side in the second direction, the third inclined surface is sharply inclined, and the distance in the second direction between the first member on which the electrolytic solution is less likely to penetrate and the third inclined surface of the second member Can be shortened, so that it is possible to suppress a decrease in the liquid pouring property in the second direction on the open side of the folded back portion.

In the storage element,
The first member has a pair of pinching portions pinching the one second member in the first direction, and a turn portion connecting the pair of pinching portions.
The end of the one side of the one second member is disposed inside the turn portion,
The one second member has a pair of the contact surfaces in contact with the pair of nipping portions, and has a pair of the first inclined surfaces extending respectively from the edge of the one side of the pair of contact surfaces. And
The second electrode in the one second member may have a metal foil and a pair of active material layers sandwiching the metal foil in the first direction.

  According to this configuration, the position of the edge of the contact surface of the second member with the first member is different, so even if the first electrode or the second electrode expands, the pressure in the stacking direction due to the expansion Can be prevented from concentrating on this edge of the second member. In addition, the active material layer and the second active material layer are provided on both surfaces of the metal foil while the portion extending along the first inclined surface of the active material layer faces the first electrode. Since the facing area of the one electrode with the pinching portion and the turning portion is increased, the energy density of the storage element can be increased.

  According to the storage element of the present embodiment, even when the first electrode and the second electrode expand, it is possible to provide the storage element in which concentration of pressure in the stacking direction caused by the expansion is suppressed.

FIG. 1 is a perspective view of a storage element according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the storage element. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. FIG. 5 is a perspective view for explaining an electrode body. FIG. 6 is a diagram for explaining the configuration of the negative electrode. FIG. 7 is a perspective view for explaining the configuration of the serpentine negative electrode. FIG. 8 is a perspective view for explaining the folded portion of the negative electrode. FIG. 9 is a schematic cross-sectional view for explaining the folded portion. FIG. 10 is a perspective view for explaining the configuration of the second member. FIG. 11 is a perspective view for explaining the configuration of the second member. FIG. 12 is a schematic cross-sectional view for illustrating the configuration of the second member. FIG. 13 is a schematic cross-sectional view for illustrating the configuration of the second member. FIG. 14 is a schematic cross-sectional view for explaining an electrode assembly according to another embodiment. FIG. 15 is a schematic cross-sectional view for explaining an electrode assembly according to another embodiment. FIG. 16 is a perspective view of a power storage device provided with the power storage element. FIG. 17 is a cross-sectional view of a conventional storage element.

  Hereinafter, an embodiment of a storage element according to the present invention will be described with reference to FIGS. 1 to 13. The storage element includes a primary battery, a secondary battery, a capacitor and the like. In the present embodiment, a chargeable / dischargeable secondary battery will be described as an example of a storage element. In addition, the name of each component (each component) of this embodiment is in this embodiment, and may differ from the name of each component (each component) in background art.

  The storage element of the present embodiment is a non-aqueous electrolyte secondary battery. More specifically, the storage element is a lithium ion secondary battery utilizing electron transfer that occurs as lithium ion moves. This type of storage element supplies electrical energy. The storage element is used singly or in plurality. Specifically, the storage element is used singly when the required output and the required voltage are small. On the other hand, when at least one of the required output and the required voltage is large, the storage element is used in the storage device in combination with another storage element. In the storage device, a storage element used for the storage device supplies electrical energy.

  As shown in FIGS. 1 to 5, the storage element includes a first member including a first electrode 21 and a plurality of second members 26 including a second electrode 22 different in polarity from the first electrode 21. And an electrode assembly 2 having the The storage element 1 also includes a case 3 for housing the electrode body 2, an external terminal 4 attached to the case 3 with at least a part exposed to the outside, and a current collector for connecting the electrode body 2 and the external terminal 4. And the body 5 is provided. The storage element 1 also includes an insulating member (contact member) 6 and the like disposed between the electrode body 2 and the case 3. Moreover, in each figure, in order to show a structure, the thickness of the electrode etc. which comprise the electrode body 2 is exaggerated and represented, and the structure of the electrode body 2 is represented typically.

  The electrode assembly 2 of the present embodiment includes a first member including the negative electrode 21 and a second member 26 including the positive electrode 22 and the separator 25. That is, in the electrode body 2 of the present embodiment, the first electrode is the negative electrode 21, the second electrode is the positive electrode 22, and the first member includes only the negative electrode 21.

  The negative electrode 21 includes a metal foil 211 and a negative electrode active material layer 212 stacked on each of both surfaces of the metal foil 211, as shown in FIGS. 4 to 8. That is, the negative electrode 21 has one metal foil 211 and a pair of negative electrode active material layers 212. The metal foil 211 of the present embodiment is, for example, a copper foil. The negative electrode 21 is in the form of a long strip and has a folded portion 23 (see FIG. 8). The second member 26 is disposed between the folded portions 23.

  The negative electrode active material layer 212 includes a negative electrode active material and a binder.

  The negative electrode active material is, for example, a carbon material such as graphite, non-graphitizable carbon, and graphitizable carbon, or a material that causes an alloying reaction with lithium ions such as silicon (Si) and tin (Sn). The negative electrode active material of the present embodiment is graphite.

  The binder used for the negative electrode active material layer 212 is, for example, polyvinylidene fluoride (PVDF), a copolymer of ethylene and vinyl alcohol, methyl polymethacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, polymethacryl Acid, styrene butadiene rubber (SBR). The binder of the present embodiment is polyvinylidene fluoride.

  The negative electrode active material layer 212 may further have a conductive aid such as ketjen black (registered trademark), acetylene black, or graphite. The negative electrode active material layer 212 of the present embodiment has no conductive support agent.

  In the following, the thickness direction of the second member 26 is taken as the X-axis direction (first direction) in the orthogonal coordinate system, and the longitudinal direction of the negative electrode 21 before being folded is taken as the Y-axis direction (second direction) in the orthogonal coordinate system. A direction intersecting with both the axial direction and the Y-axis direction is taken as the Z-axis direction of the orthogonal coordinate system.

  As shown in FIG. 7, the negative electrode 21 of the present embodiment has a folded portion 23 folded back at the turn portion 234 so as to release one side or the other side in the Y-axis direction orthogonal to the X-axis direction. The turn portion 234 connects a pair of flat portions (straps) 233 which sandwich the second member 26 in the X-axis direction. Specifically, in the negative electrode 21, the folded portions 23 adjacent to each other in a state in which the turn portion 234 is directed in the opposite direction in the Y-axis direction are continuous in a zigzag state (bellows shape) ). That is, when focusing on one folded portion (first folded portion) 23A, the first folded portion 23A and the next (rear side in FIG. 7) folded portion (second folded portion) 23B include the first Flat portions 233A and 233B between the turn portion 234A of the turnback portion 23A and the turn portion 234B of the second turnback portion 23B are shared.

  In this case, in the flat portion 233A when focusing on the first folding portion 23A, the surface on the valley folding surface side in the first folding portion 23A is the first surface 231A, and the surface on the opposite side (the surface on the mountain folding side ) Is the second surface 232A. On the other hand, in the flat portion 233B (flat portion 233B shared with the flat portion 233A of the first folded portion 23A) focusing on the second folded portion 23B, the valley folded surface side surface of the second folded portion 23B is the first And the opposite surface (the surface on the mountain fold side) is the second surface 232B. That is, in the flat portions 233A and 233B shared by the first turnback portion 23A and the second turnback portion 23B, when focusing on the first turnback portion 23A and when focusing on the second turnback portion 23B, One surface (a surface facing in the folded portion 23) 231 and a second surface (surface facing in the opposite direction in the folded portion) 232 are reversed.

  Specifically, in the negative electrode 21, flat portions 233 and turn portions 234 are alternately formed by alternately turning the strip-shaped negative electrodes 21 at predetermined intervals in the Y-axis direction. That is, mountain folds and valley folds are alternately repeated at the positions of the mountain fold lines 21A and the valley fold lines 21B which are alternately set at predetermined intervals in the longitudinal direction shown in FIG. By this, it becomes a zigzag state. Thereby, the negative electrode 21 has a plurality of flat portions 233 and a plurality of turn portions 234, and each of the plurality of flat portions 233 is arranged in parallel or substantially in parallel, and each of the plurality of turn portions 234 is adjacent The end portions on one side in the Y-axis direction of the flat portion 233 and the end portions on the other side are alternately connected. As a result, in the negative electrode 21, the first folded portions 23 </ b> A and the second folded portions 23 </ b> B are alternately and repeatedly arranged. By arranging the second member 26 between the first folded portion 23A and the second folded portion 23B, the negative electrode 21 is sandwiched between the adjacent second members 26 in the first direction. .

  Each of the plurality of flat portions 233 protrudes from one side constituting the rectangular outline of the flat portion main body 2331 having a rectangular shape and the flat portion main body 2331 as shown in FIGS. 7 and 8 (in the example of the present embodiment) , And a negative electrode tab 2332 (extending in the Z-axis direction from an edge in the Z-axis direction). The flat portion 233 of the present embodiment is a portion of the folded back portion 23 in contact with the second member 26. The flat portion main body 2331 of the flat portion 233 has a rectangular shape elongated in the Y-axis direction. In the flat portion main body 2331, both surfaces of the metal foil 211 are covered with the negative electrode active material layer 212 except for the end on the negative electrode tab 2332 side, and the metal foil 211 is exposed in the negative electrode tab 2332. That is, the negative electrode tab 2332 does not have the negative electrode active material layer 212.

  In the spirally folded negative electrode 21, the negative electrode tabs 2332 of the flat portions 233 overlap when viewed from the X-axis direction. In the negative electrode 21 of the present embodiment, each negative electrode tab 2332 is from the end in one Y-axis direction (right side in FIG. 8) at the end edge in one Z-axis direction (upper side in FIG. 8) of the flat portion body 2331. It extends in the axial direction. The negative electrode tabs 2332 extending from each of the plurality of flat portion main bodies 2331 are bundled and connected to the external terminal 4 through the current collector 5 (see FIG. 3). The bundle of negative electrode tabs 2332 in the present embodiment is welded to the current collector 5.

  The flat portion 233 of the present embodiment is a portion of the negative electrode 21 in contact with the second member 26 (see FIG. 9). The turn portion 234 of the present embodiment is a region excluding the flat portion 233 in the negative electrode 21. Further, each of the plurality of turn portions 234 is a portion where the strip-like negative electrode 21 turns (turns around) around the turn axis S (see FIG. 7) extending in the Z-axis direction in the serpentine negative electrode 21. Also in the turn portion 234, both surfaces of the metal foil 211 are covered with the negative electrode active material layer 212 except for the end portion on the negative electrode tab 2332 side. The mountain-folded surfaces of the turn portions 234 in the present embodiment are in contact with the insulating member 6. The valley folding surface of each turn portion 234 in the present embodiment is in contact with the edge of the second member 26.

  The positive electrode 22 has a metal foil 221 and a positive electrode active material layer 222 overlaid on both sides of the metal foil 221 as shown in FIGS. 4, 10 and 11. That is, the positive electrode 22 includes one metal foil 221 and a pair of positive electrode active material layers 222 sandwiching the metal foil 221 in the X-axis direction. The metal foil 221 of the present embodiment is, for example, an aluminum foil. The positive electrode 22 is sandwiched between the folded portions 23 in the serpentine negative electrode 21, and specifically, is disposed between the flat portions 233 adjacent in the X-axis direction. For this reason, the electrode body 2 of the present embodiment has a plurality of positive electrodes 22.

  The positive electrode active material layer 222 includes a positive electrode active material and a binder.

The positive electrode active material of the present embodiment is, for example, a lithium metal oxide. Specifically, the positive electrode active material is, for example, a composite oxide represented by LiaMebOc (Me represents one or more transition metals) (LiaCoyO ₂ , LiaNixO ₂ , LiaMnzO ₄ , LiaNixCoyMnzO ₂ etc.), LiaMeb XOc) d (Me represents one or more transition metals, and X represents, for example, P, Si, B, V). Polyanion compound (LiaFebPO ₄ , LiaMnbPO ₄ , LiaMnbSiO ₄ , LiaCobPO ₄ F, etc.) ). The positive electrode active material of the present embodiment is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

  The binder used for the positive electrode active material layer 222 is the same as the binder used for the negative electrode active material layer 212. The binder of the present embodiment is polyvinylidene fluoride.

  The positive electrode active material layer 222 may further have a conductive aid such as ketjen black (registered trademark), acetylene black, or graphite. The positive electrode active material layer 222 of the present embodiment has acetylene black as a conductive additive.

  Specifically, each of the plurality of positive electrodes 22 protrudes from one side of the rectangular positive electrode main body 223 and one side of the positive electrode main body 223 forming a rectangular outline (in the example of the present embodiment, from the end edge in the Z axis direction) And a positive electrode tab 224 (extending in the Z-axis direction). The positive electrode body 223 of the present embodiment has a rectangular shape elongated in the Y-axis direction. In the positive electrode main body 223, both surfaces of the metal foil 221 are covered with the positive electrode active material layer 222 except for the positive electrode tab 224 (in other words, of the outer peripheral surfaces of the metal foil 221 extending in the X axis direction and Y axis direction) The entire area except the above is covered with the positive electrode active material layer 222, and the metal foil 221 is exposed at the positive electrode tab 224 (see FIGS. 12 and 13). That is, the positive electrode tab 224 does not have the positive electrode active material layer 222.

  In addition, the positive electrode active material layer 222 in the positive electrode main body 223 has a YZ plane (Y axis and Z direction) from the negative electrode active material layer 212 of the flat portion 233 facing in the X axis direction (specifically, facing via the separator 25). Small in the plane) direction including the axis. That is, the positive electrode active material layer 222 of the positive electrode main body 223 faces the negative electrode active material layer 212 of the flat portion 233 in the entire region, and the negative electrode active material layer 212 of the flat portion 233 has the positive electrode body 223 in the region excluding the peripheral portion. It faces the positive electrode active material layer 222.

  The positive electrode main body 223 of this embodiment has a central portion 2230 located at the center in the Y-axis direction, a first end portion 2231 continuous with the central portion 2230 on one side in the Y-axis direction, and the other end side in the Y-axis direction The second end 2232 is continuous with the central portion 2230 (see FIGS. 10 to 13). The thickness of central portion 2230 of positive electrode main body 223 in the X-axis direction is uniform or substantially uniform. The thickness of the first end portion 2231 of the positive electrode main body 223 in the X-axis direction is thinner toward one side in the Y-axis direction. The thickness of the second end 2232 of the positive electrode main body 223 in the X-axis direction is thinner toward the other side in the Y-axis direction. The positive electrode body 223 according to the embodiment has a symmetrical shape with reference to a central axis C which passes through the center in the thickness direction in the X-axis direction and extends in the Y-axis direction (see FIGS. 12 and 13).

  Hereinafter, when it is necessary to distinguish between the second members 26 adjacent in the X-axis direction, the second member 26 sandwiched by the first folded portion 23A is referred to as a first second member 26A, and the second folded The second member 26 sandwiched by the portions 23B is referred to as a second second member 26B (see FIG. 9). Further, when it is necessary to distinguish, the positive electrode 22 included in the first second member 26A is referred to as a first positive electrode 22A, and the positive electrode 22 included in the second second member 26B is referred to as a second positive electrode 22B. It is called.

  In the first positive electrode 22A of the present embodiment, portions of the outer peripheral surface of the positive electrode body 223 corresponding to the central portion 2230 are a pair of flat surfaces 2230S extending in parallel to the central axis C. The dimensions in the Y-axis direction of the pair of flat surfaces 2230S are the same.

  The portion of the outer peripheral surface of the positive electrode main body 223 in the first positive electrode 22A corresponding to the first end 2231 is continuous with the edge of one side in the Y-axis direction of the flat surface 2230S of the first positive electrode 22A. It is an inclined surface 2231 S that extends obliquely with respect to the central axis C. The inclined surfaces 2231S are also provided in the same manner as the flat surfaces 2230S. The inclined surface 2231S of the positive electrode main body 223 in the first positive electrode 22A is inclined toward the central axis C by the inclination angle θ1 with respect to the virtual surface R1 including the flat surface 2230S continuous thereto, as described above The thickness of the first end 2231 in the X-axis direction is thinner toward one side in the Y-axis direction. In addition, the dimension in the Y-axis direction of a pair of inclined surface 2231S in 22 A of 1st positive electrodes is the same.

  Further, the portion of the outer peripheral surface of the positive electrode main body 223 in the first positive electrode 22A corresponding to the second end 2232 is continuous with the other edge of the flat surface 2230S of the first positive electrode 22A in the Y-axis direction. It is an inclined surface 2332S that extends obliquely with respect to the central axis C. The inclined surfaces 2232S are also provided in the same manner as the flat surfaces 2230S. The inclined surface 2232S of the first positive electrode 22A is inclined toward the central axis C by the inclination angle θ2 with respect to the virtual surface R1 including the flat surface 2230S continuous to the first positive electrode 22A. The thickness of the end 2231 in the X-axis direction is thinner toward the other side in the Y-axis direction. The dimension in the Y-axis direction of the pair of inclined surfaces 2332S in the first positive electrode 22A is the same.

  In the first positive electrode 22A, since the inclination angle θ1 is smaller than the inclination angle θ2, the inclined surface 2231S inclines more gently than the inclined surface 2232S, and the first end 2231S is elongated than the second end 2232 It has a shape.

  On the other hand, also in the positive electrode main body 223 of the second positive electrode 22B of the present embodiment, a portion corresponding to the central portion 2230 in the outer peripheral surface is a pair of flat surfaces 2230S extending in parallel to the central axis C. The dimensions in the Y-axis direction of the pair of flat surfaces 2230S are the same (see FIG. 13).

  A portion corresponding to the first end 2231 of the outer peripheral surface of the positive electrode main body 223 in the second positive electrode 22B is continuous with the one edge of the flat surface 2230S in the second positive electrode 22B in the Y axis direction. , And is an inclined surface 2231S extending obliquely with respect to the central axis C. The inclined surfaces 2231S are also provided in the same manner as the flat surfaces 2230S. The inclined surface 2231S of the second positive electrode 22B is inclined toward the central axis C by the inclination angle θ3 with respect to the virtual surface R1 including the flat surface 2230S continuous with the first positive electrode 22B. The thickness of the end 2231 in the X-axis direction is thinner toward one side in the Y-axis direction. In addition, the dimension in the Y-axis direction of a pair of inclined surface 2231S in 2nd positive electrode 22B is the same (refer FIG. 13).

  Furthermore, a portion of the outer peripheral surface of the positive electrode main body 223 in the second positive electrode 22B that corresponds to the second end 2232 is continuous with the other end of the flat surface 2230S in the Y-axis direction, and Is an inclined surface 2332S extending obliquely. The inclined surfaces 2232S are also provided in the same manner as the flat surfaces 2230S. The inclined surface 2232S in the second positive electrode 22B is inclined toward the central axis C by the inclination angle θ4 with respect to the virtual surface R1 including the flat surface 2230S continuous with the first positive electrode 22B. The thickness of the end 2231 in the X-axis direction is thinner toward the other side in the Y-axis direction. In addition, the dimension in the Y-axis direction of a pair of inclined surface 2332S in 2nd positive electrode 22B is the same.

  In the second positive electrode 22B, since the inclination angle θ4 is smaller than the inclination angle θ3, the inclined surface 2232S inclines more gently than the inclined surface 2231S, and the second end 2232 is elongated than the first end 2231. It has a shape.

  In the positive electrode 22 of the present embodiment, the dimension of the first positive electrode 22A in the Y-axis direction is the same as the dimension of the second positive electrode 22B in the Y-axis direction. Further, in the positive electrode 22 of the present embodiment, the dimension in the Y-axis direction of the central portion 2230 is the same in both the first positive electrode 22A and the second positive electrode 22B (see FIG. 9). Furthermore, in each of the first positive electrode 22A and the second positive electrode 22B, the thickness in the X-axis direction of the central portion 2230 is the same. As described above, the central portion 2230 of the first positive electrode 22A is the same as the central portion 2230 of the second positive electrode 22B.

  Further, in the positive electrode 22 of the present embodiment, the dimension of the first end portion 2231 of the first positive electrode 22A in the Y-axis direction is larger than the dimension of the first end portion 2231 of the second positive electrode 22B in the Y-axis direction ( 12 and 13). Therefore, the inclination angle θ1 is smaller than the inclination angle θ3. Accordingly, the inclined surface 2231S of the first positive electrode 22A is more gently inclined than the inclined surface 2231S of the second positive electrode 22B, and the first end 2231 of the first positive electrode 22A is the same as that of the second positive electrode 22B. It has a more elongated shape than the first end 2231.

  Furthermore, the dimension in the Y-axis direction of the second end 2232 of the second positive electrode 22B is larger than the dimension in the Y-axis direction of the second end 2232 of the first positive electrode 22A. Since the inclination angle θ4 is smaller than the inclination angle θ2, the inclined surface 2232S of the second positive electrode 22B inclines more gently than the inclined surface 2232S of the first positive electrode 22A, and the second end of the second positive electrode 22B. 2232 has an elongated shape than the second end 2232 of the first positive electrode 22A.

  In the positive electrode 22 of the present embodiment, the dimension of the first end 2213 of the first positive electrode 22A in the Y-axis direction is the same as the dimension of the second end 2232 of the second positive electrode 22B in the Y-axis direction. The dimension in the Y-axis direction of the second end 2232 of the first positive electrode 22A is the same as the dimension in the Y-axis direction of the first end 2231 of the second positive electrode 22B.

  Further, in the positive electrode 22 of the present embodiment, the inclination angle θ1 and the inclination angle θ4 are the same, and the inclination angle θ2 and the inclination angle θ3 are the same. Therefore, the second end 2232 of the second positive electrode 22B is obtained by inverting the first end 2231 of the first positive electrode 22A. The first end 2231 of the second positive electrode 22B is an inversion of the second end 2232 of the first positive electrode 22A. Furthermore, as described above, since the central portion 2230 of the first positive electrode 22A is the same as the central portion 2230 of the second positive electrode 22B, the shape of the positive electrode body 223 of the second positive electrode 22B is the first positive electrode. The shape is the same as the inverted shape of the positive electrode body 223 of 22A.

  Further, in the positive electrode 22 of the present embodiment, as described above, the entire area of the outer peripheral surface of the metal foil 221 extending in the X-axis direction and the Y-axis direction is covered with the positive electrode active material layer 222. Specifically, in the positive electrode 22 of the present embodiment, the metal foil 221 and the positive electrode active material layer 222 in each of the first positive electrode 22A and the second positive electrode 22B are a central portion 2230, a first end 2231, and a second It extends across the end 2232. More specifically, in any of the first positive electrode 22A and the second positive electrode 22B, the metal foil 221 extending along the central axis C and the positive electrode active material layer 222 covering both surfaces of the metal foil 221 have inclined surfaces. It extends along the entire area of 2231S and inclined surface 2232S. For example, the thickness of the metal foil 221 in the X-axis direction is uniform or substantially uniform in any of the central portion 2230, the first end portion 2331, and the second end portion 2332. The thickness of the positive electrode active material layer 222 in the X-axis direction is uniform or substantially uniform at the central portion 2230. The thickness of the positive electrode active material layer 222 in the X-axis direction is thinner at one end in the first end portion 2331 in the Y-axis direction. Further, the thickness of the positive electrode active material layer 222 in the X-axis direction is thinner at the second end portion 2331 toward the other side in the Y-axis direction.

  In the electrode body 2, the positive electrode tabs 224 of the respective positive electrodes 22 overlap when viewed from the X-axis direction. In the positive electrode 22 according to the present embodiment, each positive electrode tab 224 has one of the Y axis directions (the position of the negative electrode tab 2332 with respect to the flat portion main body 2331) at one end (upper side in FIG. Extends from the end of the opposite side in FIG. 5) in the Z-axis direction. The positive electrode tabs 224 extending from each of the plurality of positive electrode bodies 223 are bundled and connected to the external terminal 4 via the current collector 5. The bundle of positive electrode tabs 224 in the present embodiment is welded to the current collector 5 in the same manner as the bundle of negative electrode tabs 2332 (see FIG. 3).

  The separator 25 is a member having an insulating property, and is disposed between the negative electrode 21 and the positive electrode 22 (see FIG. 9). Thereby, in the electrode body 2, the negative electrode 21 and the positive electrode 22 are mutually insulated. Further, the separator 25 holds the electrolytic solution in the case 3. Thereby, at the time of charge and discharge of the storage element 1, lithium ions can move between the negative electrode 21 and the positive electrode 22 facing each other across the separator 25.

The separator 25 is in the form of a band, and is made of, for example, a porous film of polyethylene, polypropylene, cellulose, polyamide or the like. In the separator 25 of the present embodiment, an inorganic layer containing inorganic particles such as SiO ₂ particles, Al ₂ O ₃ particles, boehmite (alumina hydrate) and the like is provided on a substrate formed of a porous film. It is formed of The base material of the separator 25 of the present embodiment is formed of, for example, polyethylene.

  The separator 25 of the present embodiment is flexible. Moreover, the thickness of the separator 25 of this embodiment is uniform.

  Furthermore, the separator 25 of the present embodiment covers the positive electrode 22. Specifically, the separator 25 covers the entire positive electrode main body 223 so as to sandwich it in the X-axis direction. As shown in FIG. 5, FIG. 10 and FIG. 11, this separator 25 is folded at the center in the longitudinal direction with the positive electrode 22 sandwiched between the rectangular ones, and the three sides excluding the fold portion (Each edge) is joined (adhesion, welding, etc.). At this time, the positive electrode tab 224 protrudes from the folded back separator 25 (see FIG. 5), and the bonding is performed avoiding the positive electrode tab 224.

  The separator 25 sandwiching the positive electrode 22 has a rectangular shape when viewed from the X-axis direction, and the dimension in the Z-axis direction is larger than the dimension of the flat portion 233 of the negative electrode 21 and the dimension in the Y-axis direction is also flat Larger than 233 dimensions. As described above, in the electrode body 2 of the present embodiment, the positive electrode 22 and the separator 25 with the positive electrode 22 sandwiched therebetween constitute the second member 26. In addition, since the separator 25 of the present embodiment has flexibility, the separator 25 in a state in which the positive electrode 22 is sandwiched, that is, the second member 26 has a shape along the shape of the positive electrode 22.

  The dimensions in the Y-axis direction of the adjacent second members 26 in the X-axis direction are the same (see FIG. 9). The dimension of the second member 26 in the Y-axis direction is the distance between one end of the second member 26 in the Y-axis direction and the other end. The dimension of the second member 26 of the present embodiment in the Y-axis direction is the outermost edge of the ridge-folded surface of the fold portion of the separator 25 and the edge of the second portion 26 opposite to the fold portion of the separator 25 Distance between The end edges on one side of the second members 26 adjacent in the X axis direction are aligned in the Y axis direction, and the end edges on the other side of the second members 26 adjacent in the X axis direction are also in the Y axis direction It is complete.

  The second member 26 is disposed between each pair of flat portions 233 adjacent in the X-axis direction (see FIG. 9). As a result, the positive electrode 22 faces the respective surfaces of the flat portion 233 of the negative electrode 21. In other words, the second members 26 adjacent in the X-axis direction sandwich the flat portion 233 of the negative electrode 21.

  The second member 26 also has a contact surface 260 in contact with the negative electrode 21. The second member 26 of the present embodiment is in contact with the flat portion 233 at the contact surface 260. Specifically, the second member 26 is in contact with each of the pair of flat portions 233 at the pair of contact surfaces 260 adjacent in the X-axis direction. The central portion including the pair of contact surfaces 260 of the first second member 26A is the same as the central portion including the pair of contact surfaces 260 of the second second member 26B.

  In the storage element 1 of the present embodiment, the end of one side of the first second member 26A in the Y-axis direction is continuous with the central portion of the first second member 26A on one side in the Y-axis direction. . The other end is disposed inside the turn portion 234A. The other end of the first second member 26A in the Y-axis direction is continuous with the central portion of the first second member 26A on the other side in the Y-axis direction. The end on one side is disposed between the pair of flat portions 233 (the other side of the folded portion 23A).

  The other end of the second second member 26B in the Y-axis direction is continuous with the central portion of the second second member 26B on the other side in the Y-axis direction. The other end is disposed inside the turn portion 234B. One end of the first second member 26A in the Y-axis direction is continuous with the central portion of the second second member 26B on one side in the Y-axis direction. The end on one side is disposed between the pair of flat portions 233 (one side of the folded portion 23B).

  The position of one end edge 261 in the Y-axis direction of the contact surface 260 of the first second member 26A and the position of the one end edge 262 in the Y-axis direction of the contact surface 260 of the second second member 26B It is different from The edge 261 on one side of the contact surface 260 of the first second member 26A of this embodiment is closer to the other edge 262 in the Y-axis direction than the edge 262 on one side of the contact surface 260 of the second second member 26B. Located on the side.

  As described above, the second member 26 of the present embodiment has a shape following the shape of the positive electrode 22, and the positive electrode 22 passes through the central axis C in the X-axis direction (the center in the thickness direction in the X-axis direction). And, it has a symmetrical shape about a central axis C) extending in the Y-axis direction. Therefore, the second member 26 of the present embodiment has a symmetrical shape about the central axis C in the X-axis direction.

  The first second member 26A extends to one side from the edge 261 on one side in the Y-axis direction of the contact surface 260 of the first second member 26A, and itself and an imaginary surface R2 including the contact surface 260 The inclined surface (first inclined surface) 261S is inclined such that the distance in the X-axis direction of the light source increases toward one side. The second second member 26B extends from one end 262 in the Y-axis direction of the contact surface 260 of the second second member 26B to one side, and also with itself and an imaginary surface R2 including the contact surface 260. Has an inclined surface (second inclined surface) 262S which is inclined such that the distance in the X-axis direction of the element increases toward one side. The virtual surface R2 is obtained by translating the virtual surface R1 in the X-axis direction.

  The first second member 26A extends from the other end 263 of the contact surface 260 of the first second member 26A in the Y-axis direction to the other side, and is a distance from the virtual surface R2 including the contact surface 260 Has an inclined surface (third inclined surface) 263S inclined so as to increase toward the other side. The second second member 26B extends from the other end 264 of the contact surface 260 of the second member 26B in the Y-axis direction to the other side, and is a distance from an imaginary surface R2 including the contact surface 260 Has an inclined surface (fourth inclined surface) 264S which is inclined so as to increase toward one side.

  The first second member 26A of the present embodiment has a pair of contact surfaces 260 and a pair of inclined surfaces 261S extending respectively from the end edge 261 of one side of the pair of contact surfaces 260, and a pair of There are a pair of inclined surfaces 263S extending respectively from the edge 263 on the other side of the contact surface 260. Similarly, the second second member 26 B has a pair of contact surfaces 260 and a pair of inclined surfaces 262 S extending from the end edge 262 of one side of the pair of contact surfaces 260, and a pair of contact surfaces 260. There are a pair of inclined surfaces 264S extending respectively from the end edge 264 of the other side.

  The inclination angle θ5 of the inclined surface 261S with respect to the virtual surface R2 is smaller than the inclination angle θ6 of the inclined surface 262S with respect to the virtual surface R2, and the inclined surface 261S is inclined more gently than the inclined surface 262S. The inclination angle θ8 of the inclined surface 264S with respect to the virtual surface R2 is smaller than the inclination angle θ7 of the inclined surface 263S with respect to the virtual surface R2, and the inclined surface 264S is inclined more gently than the inclined surface 263S. The inclination angle θ5 of the inclined surface 261S with respect to the virtual surface R2 is smaller than the inclination angle θ7 of the inclined surface 263S with respect to the virtual surface R2, and the inclined surface 261S is inclined more gently than the inclined surface 263S. In the second member 26 of the present embodiment, the inclination angle θ5 and the inclination angle θ8 are the same, and the inclination angle θ6 and the inclination angle θ7 are the same. Further, in the second member 26 of the present embodiment, the inclination angle θ1 and the inclination angle θ5 are substantially the same, the inclination angle θ2 and the inclination angle θ7 are substantially the same, and the inclination angle θ3 and the inclination angle θ6 are substantially The same is true, and the inclination angle θ4 and the inclination angle θ8 are substantially the same.

  In the first second member 26A, the first positive electrode 22A extends along the contact surface 260 and extends along the inclined surface 261S and the inclined surface 263S, respectively, and the negative electrode 21 and the entire area in the Y-axis direction. Are facing each other. Similarly, in the second second member 26B, the second positive electrode 22B extends along the contact surface 260, and extends along the inclined surface 262S and the inclined surface 264S, respectively, and throughout the Y-axis direction. It faces the negative electrode 21.

  In the storage element 1 of the present embodiment, the inclination angle θ5 and the inclination angle θ8 are the same, and the inclination angle θ6 and the inclination angle θ7 are the same. Therefore, the other end of the second second member 26B in the Y-axis direction is the end of one end of the first second member 26A in the Y-axis direction inverted. Further, the end on one side in the Y-axis direction of the second second member 26B is obtained by inverting the end on the other side in the Y-axis direction of the first second member 26A.

  Referring back to FIGS. 1 to 4, the case 3 has a case main body 31 having an opening, and a lid plate 32 that closes (closes) the opening of the case main body 31. In the case 3, an inner space is defined by the case body 31 and the cover plate 32. The case 3 accommodates the electrolytic solution together with the electrode assembly 2 in the internal space.

This electrolyte is a non-aqueous electrolyte. Specifically, the electrolytic solution is obtained by dissolving an electrolyte salt in an organic solvent. The organic solvent is, for example, cyclic carbonates such as propylene carbonate and ethylene carbonate, linear carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. The electrolyte salt is LiClO ₄ , LiBF ₄ , LiPF ₆ or the like. The electrolyte solution of the present embodiment is 1 mol / L of LiPF ₆ in a mixed solvent prepared by adjusting propylene carbonate, dimethyl carbonate and ethyl methyl carbonate in a ratio of propylene carbonate: dimethyl carbonate: ethyl methyl carbonate = 3: 2: 5. Was dissolved.

  Case 3 is formed of a metal resistant to the above-described electrolyte solution. The case 3 of the present embodiment is formed of, for example, an aluminum-based metal material such as aluminum or an aluminum alloy.

  The case main body 31 includes a plate-like closing portion 311 and a cylindrical trunk portion (peripheral wall) 312 connected to the peripheral edge of the closing portion 311.

  The closing portion 311 is positioned at the lower end of the case body 31 when the case body 31 is disposed in the posture in which the opening is directed upward (that is, the bottom wall portion of the case body 31 when the opening faces upward) ) Site. The closed portion 311 of the present embodiment is rectangular.

  The body portion 312 has a square tube shape, more specifically, a flat square tube shape. The body portion 312 has a pair of long wall portions 313 extending from the long side in the peripheral edge of the closing portion 311 and a pair of short wall portions 314 extending from the short side in the peripheral edge of the closing portion 311. By connecting the short wall portions 314 to the corresponding end portions of the pair of long wall portions 313 (specifically, facing in the X-axis direction), the rectangular cylindrical body portion 312 is formed.

  As described above, the case main body 31 has a rectangular tube shape (that is, a bottomed rectangular tube shape) in which one end in the opening direction (Z-axis direction) is closed. The electrode body 2 is accommodated in the case main body 31 such that the flat portions 233 of the negative electrode 21 are parallel (substantially parallel) to the long wall portion 313 (that is, the turn portions 234 face the short wall portion 314). (See FIG. 4).

  The lid plate 32 is a member that closes the opening of the case main body 31. The outline shape of the lid plate 32 is a shape corresponding to the opening peripheral edge portion 310 (see FIG. 2) of the case main body 31. That is, the cover plate 32 is a rectangular plate material long in the Y-axis direction.

  The external terminal 4 is a portion electrically connected to an external terminal of another storage element or an external device. Thus, the external terminal 4 is formed of a conductive member. Further, the external terminal 4 is formed of a metal material having high weldability. For example, the external terminal 4 of the positive electrode is formed of an aluminum-based metal material such as aluminum or an aluminum alloy, and the external terminal 4 of the negative electrode is formed of a copper-based metal material such as copper or a copper alloy. The external terminal 4 of the present embodiment is attached to the cover plate 32 in a state where at least a part is exposed to the outside of the case 3.

  The insulating member 6 is formed of an insulating resin. Concretely, the insulating member 6 is formed in the shape of a bag in which the lid plate 32 side is opened by bending the sheet-like member having the insulating property which is cut into a predetermined shape (see FIG. 2). The insulating member 6 of the present embodiment is shaped like a bag along the case body 31. The flat portions 233 of the negative electrode 21 and the second member 26 of the bag-shaped insulating member 6 are substantially parallel to the portion (the wall-shaped portion facing in the X-axis direction) corresponding to the long wall portion 313 of the insulating member 6. The electrode assembly 2 is accommodated such that each turn 234 is opposed to a portion (a wall-shaped portion facing in the Y-axis direction) corresponding to the short wall portion 314 in the insulating member 6.

  According to the storage element 1 described above, the positions of the end edges 261 and 262 on one side of the contact surface 260 of the second member 26 with the negative electrode 21 and the end edges 263 and 264 on the other side of the contact surface 260 are different. Even when the negative electrode 21 and the positive electrode 22 expand during use of the storage element 1 in which the dimensions of the second member 26 in the Y-axis direction are equal, the pressure in the Y-axis direction (the stacking direction of the positive electrode 22) Concentration on the edge of the two members 26 can be suppressed.

  Further, in the electrode body 2 of the present embodiment, the positive electrode 22 extends along the inclined surface 261S in addition to the contact surface 260, so the energy density of the storage element 1 can be increased.

  More specifically, in the configuration in which the end edge 261 of the contact surface 260 of the second member 26 with the negative electrode 21 is disposed on the inner side, compared with the configuration in which the end edge 261 of the contact surface 260 is disposed on the outer side. Since the dimension of the contact surface 260 in the Y-axis direction is reduced, the facing area between the negative electrode 21 and the positive electrode 22 becomes narrow even if the positive electrode 22 extends along the contact surface 260, and as a result, the energy of the storage element 1 Density may decrease.

  On the other hand, in the electrode body 2 of the present embodiment, a portion of the positive electrode 22 extending along the inclined surface (first inclined surface) 261 S faces the negative electrode 21, whereby the facing area of the negative electrode 21 and the positive electrode 22 Can be increased, so that the energy density of the storage element 1 can be increased. The energy density is volume energy density, and is the capacity of the battery per unit volume.

  Furthermore, in the electrode body 2 of the present embodiment, since the positive electrode 22 extends along the inclined surface 262S in addition to the inclined surface 261S, the energy density of the storage element 1 is increased. It is possible to suppress concentration of pressure in the Y-axis direction due to expansion at the edge of the positive electrode 22.

  More specifically, when the positions of the edges 261 and 263 of the contact surface 260 of the second member 26 adjacent to the X-axis direction with the negative electrode 21 are different in the Y-axis direction, the edges 261 and 263 are aligned. Even when the positive electrode 22 extends along the contact surface 260 as compared with the configuration described above, the opposing area of the negative electrode 21 and the positive electrode 22 is narrowed, which may reduce the energy density of the storage element 1. In addition, when the serpentine negative electrode 21 and the strip-like positive electrode 22 are combined, there is a problem that current concentration tends to occur at the end of the positive electrode 22 during charge and discharge. If current concentration occurs in this manner, the end of the positive electrode 22 may expand, which may cause a larger pressure to be applied to the end of the positive electrode 22 compared to the region excluding the end of the positive electrode 22. is there.

  On the other hand, in the electrode body 2, the inclined surface 261S and the portion extending along the inclined surface 262S of the positive electrode 22 face the negative electrode 21 so that the facing area between the negative electrode 21 and the positive electrode 22 becomes wide. The energy density of the element 1 can be increased. Moreover, since the positions of the end edges 261 and 262 of the contact surface 260 of the second member 26 adjacent to the negative electrode 21 in the X axis direction are different, the storage element 1 having the same dimension in the Y axis direction of the second member 26 is used. In this case, even if the negative electrode 21 and the positive electrode 22 expand, the pressure in the Y-axis direction resulting from the expansion can be prevented from being concentrated at this edge of the second member 26. In particular, when the zigzag negative electrode 21 and the strip-like positive electrode 22 are combined, current concentration at the end of the positive electrode 22 can be effectively suppressed.

  In the configuration in which the end of one side of the first second member 26A is surrounded by the turn portion 234A, when the negative electrode 21 or the positive electrode 22 expands, the end of one side of the contact surface 260 of the second member 26 This edge 261 is likely to bite into the negative electrode 21 because a greater pressure is applied to the edge 261 than to the edge 262 on the other side. According to this configuration, at the end edge 261 of one side of the contact surface 260 of the first second member 26A to which a large pressure is applied by being surrounded by the turn portion 234, the inclined surface (first inclined surface) 261A is relaxed. The edge 261 is prevented from biting into the negative electrode 21 by making the edge including the edge 261 on one side of the contact surface 260 loose.

  Further, in the electrode body 2 of the present embodiment, the inclined surfaces 261 S and 264 S of the end portions of the end portions of the second member 26 disposed on the turn portion 234 of the turn back portion 23 are gently inclined. The inclined surfaces 262S and 263S of the ends disposed on the open side are steeply inclined to ensure the supply amount of the electrolytic solution to the turn portion 234 and also to reduce the liquid injection from the open side of the folded portion 23 It is also suppressed.

  More specifically, since the space between the negative electrode 21 and the contact surface 260 of the second member 26 is narrow, the electrolytic solution is likely to permeate into the electrode body 2 through this region, but the negative electrode 21 and the second member 26 Since the space between the inclined surface 261S and the like is wider than the space between the negative electrode 21 and the contact surface 260, the electrolytic solution is less likely to penetrate into the electrode body 2 through this region. On the other hand, since the region inside the turn portion 234 is surrounded by the negative electrode 21, it is difficult to supply the electrolytic solution to this region. In addition, improvement of the liquid injection property is also required in the area other than the inner side of the turn portion 234.

  On the other hand, in the electrode body 2 of the present embodiment, the end portion on one side of the first second member 26A has the inclined surface (first inclined surface) 261S, so that the end portion is the inclined surface 261S. Of the turn 234, ie, the area of the turn 234, rather than the case where the end of one side of the first second member 26A coincides with the end of one side of the contact surface 260). The area between the valley folding surface and the end of the first second member 26A is widened, and the electrolyte is likely to flow from the outside into the area inside the turn portion 234. Thus, in such a configuration, the supply amount of the electrolytic solution to the inside of the turn portion 234 is increased. In addition, the inclined surface (third inclined surface) 263S of the other end of the first second member 26A is sharply inclined to make the negative electrode 21 and the second member 26 inclined so that the electrolyte does not easily penetrate. Since the distance in the Y-axis direction from 263S is shortened, it is possible to suppress the decrease in the liquid injection property in the Y-axis direction on the open side of the folded back portion 23.

  Furthermore, in the electrode body 2 of the present embodiment, the positive electrode active material layer 222 of the positive electrode 22 extends along the pair of inclined surfaces 261S of the first second member 26A, whereby the energy density of the storage element 1 can be increased. It can be increased.

  As described above, when the positions of the end edges 261 and 262 of the contact surface 260 of the second member 26 adjacent to the X axis direction with the negative electrode 21 are made different in the Y axis direction, the negative electrode 21 of the adjacent second member 26 Even when the positive electrode 22 extends along the contact surface 260, the opposing area of the negative electrode 21 and the positive electrode 22 becomes narrower, as compared with the configuration in which the end edges 261 and 262 of the contact surface 260 are aligned. The energy density of the element 1 may be reduced.

  On the other hand, in the electrode body 2, the positions of the end edges 261 and 262 of the contact surface 260 of the second member 26 with the negative electrode 21 are different, so even if the negative electrode 21 and the positive electrode 22 expand, the expansion is caused. Pressure in the Y-axis direction (stacking direction) can be prevented from concentrating on the edges 261 and 262 of the second member 26, and along the inclined surface (first inclined surface) 261S of the positive electrode active material layer 222 The extending portion faces the negative electrode 21 and the positive electrode active material layer 222 is provided on both sides of the metal foil 220, so that the facing area of the positive electrode active material layer 222 in the positive electrode 22 and the flat portion 233 and the turn portion 234 in the negative electrode 21. Can be increased, so that the energy density of the storage element 1 can be increased.

  The storage element of the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and part of the configuration of one embodiment can be replaced with the configuration of another embodiment. In addition, some of the configuration of an embodiment can be deleted.

  In the electrode body 2 of the above embodiment, both the end of the second member 26 disposed in the turn 234 and the end of the second member 26 disposed on the open side of the folded portion 23 have inclined surfaces. However, the end of the second member 26 disposed on the open side of the folded portion 23 may not have an inclined surface (see FIG. 9). Specifically, the end of the second member 26 disposed in the turn portion 234A of the first second member 26A has the inclined surface 261S, and the opening of the second folded portion 23B of the second second member 26B. The end of the second member 26 disposed on the side does not have an inclined surface, and the end edge of the end of the second member 26 in the second second member 26B is identical to the edge 262 of the contact surface 260. It may be done. Even in this case, in the second member 26 adjacent in the X-axis direction, the end edges 261 and 262 on one side of the contact surface 260 of the second member 26 with the negative electrode 21 and the other end of the contact surface 260 Since the positions of the edges 263 and 264 are different, even if the negative electrode 21 or the positive electrode 22 expands during use of the storage element 1 having the same dimension in the Y-axis direction of the second member 26, the expansion in the Y-axis direction Concentration of pressure on the edge of the second member 26 can be suppressed.

  Further, in the electrode body 2 of the above embodiment, the end edges on one side of the adjacent second members 26 in the X-axis direction are aligned in the Y-axis direction, and the other side of the adjacent second members 26 in the X-axis direction The edges were also aligned in the Y-axis direction, but the positions of these edges may be different. Specifically, the second members 26 having equal dimensions in the Y-axis direction are arranged adjacent to each other in the X-axis direction, and the end edges on one side thereof are arranged to be different in the Y-axis direction. In the second members 26 axially adjacent to each other, the end edges 261 and 262 on one side of the contact surface 260 may be made different in the Y-axis direction. Also in this case, since the positions of the end edges 261 and 262 of the one side of the contact surface 260 of the second member 26 with the negative electrode 21 are different, during use of the storage element 1 having the same dimension in the Y axis direction of the second member 26 In addition, even if the negative electrode 21 and the positive electrode 22 expand, the pressure in the Y-axis direction resulting from the expansion can be suppressed from being concentrated at the edge of the second member 26.

  In the electrode body 2 of the above embodiment, the valley-folded surface of each turn 234 is in contact with the edge of the second member 26, but the valley-folded surface and the edge of the second member 26 are separated May be

  In the positive electrode 22 of the above embodiment, the first end 2231 has the pair of inclined surfaces 2231S, and the second end 2232 has the pair of inclined surfaces 2232S (see FIG. 12 and FIG. 13), At least one of the one end 2231 and the second end 2232 may have only one inclined surface. Specifically, the first end portion 2231 may have a flat surface extending from the flat surface 2230S to one side in the Y-axis direction and one inclined surface 2231S. In other words, a portion of the outer peripheral surface of the positive electrode 22 corresponding to the first end 2231 may be inclined with respect to a virtual surface including the flat surface 2230S on only one side in the X-axis direction. Thus, one end of the second member 26 in the Y-axis direction may have a flat surface extending from the contact surface 260 to one side in the Y-axis direction, and one inclined surface 261S.

  Further, in the positive electrode 22 of the above embodiment, the inclination angle θ1 of the first end 2231 of the first positive electrode 22A and the inclination angle θ4 of the second end 2232 of the second positive electrode 22B are the same. The inclination angle θ2 of the second end 2232 of the positive electrode 22A and the inclination angle θ3 of the first end 2231 of the second positive electrode 22B are the same, but the inclination angle of the first end 2231 of the first positive electrode 22A 1 and the inclination angle θ4 of the second end 2232 of the second positive electrode 22B are different, or the second end 2232 inclination angle θ2 of the first positive electrode 22A and the first end 2231 of the second positive electrode 22B. The inclination angle θ3 may be different. Thereby, in the second member 26, the inclination angle θ5 of the first second member 26A is different from the inclination angle θ8 of the second second member 26B, or the inclination angle θ6 of the first second member 26A and The inclination angle θ7 of the second second member 26B may be different.

  In the first second member 26A, the positive electrode 22 extends along the contact surface 260, and extends along the entire area of the inclined surface 261S and the entire area of the inclined surface 263S, and the entire area in the Y axis direction However, the positive electrode 22 may extend along at least a part of the inclined surface 261S and the inclined surface 263S, and may be opposed to the negative electrode 21 in the entire area in the Y-axis direction. Also in this case, it is possible to increase the facing area of the negative electrode 21 and the positive electrode 22 by the amount that a portion of the positive electrode 22 extending along at least a part of the inclined surface 261S or the inclined surface 263S faces the negative electrode 21. Also, the positive electrode 22 may extend along only the contact surface 260.

  The separator 25 of the above-described embodiment includes the fold portion, but may have a configuration that does not include the fold portion, for example, a configuration in which two sheet-like members are joined.

  In the storage element 1 of the above embodiment, the first member is configured of the negative electrode 21 and the second member 26 is configured of the positive electrode 22 and the separator 25. However, the separator 25 may be included in the first member. In this case, the separator 25 may be in the same zigzag shape as the negative electrode 21 (in a zigzag shape having a plurality of folded portions). In this case, the dimension of the second member 26 in the Y-axis direction is the dimension of the positive electrode 22 in the Y-axis direction.

  Furthermore, when the separator 25 is included in the first member and the second member 26 does not include the separator 25, the contact surface 260 of the second member 26 is the flat surface 2230S of the positive electrode 22, and the inclined surface of the second member 26 261S and the inclined surface 262S are the inclined surface 2231S of the positive electrode 22, and the inclined surface 263S and the inclined surface 264S of the second member 26 are the inclined surface 2332S of the positive electrode 22.

  Further, in the storage element 1 of the above embodiment, the separator 25 in a state of sandwiching the positive electrode 22 is rectangular when viewed from the X-axis direction, and the dimension in the Z-axis direction is larger than the dimension of the flat portion 233 of the negative electrode 21. The dimension in the Y-axis direction is smaller than the dimension of the flat portion 233, but the dimension in the Z-axis direction may be approximately the same as or smaller than the dimension of the flat portion 233 of the negative electrode 21 The dimensions may be substantially the same as the dimensions of the flat portion 233.

  In the storage element 1 of the above embodiment, one of the electrodes (in the example of the above embodiment, the negative electrode 21) is in a zigzag state, but it is not limited to this configuration. In the electrode body 2, one of the electrodes may have at least one folded portion 23. Specifically, as shown in FIG. 14, the negative electrode 21 may have a plurality of folded portions 23 each formed of an independent negative electrode 21. In this case, the second member 26 may also be sandwiched between the folded portions 23 arranged adjacent to each other in the X-axis direction. Since the positions of the end edges 261 and 262 on one side of the contact surface 260 with the negative electrode 21 of the second member 26 and the end edges 263 and 264 on the other side of the contact surface 260 also differ according to this configuration, the second member 26 Even when the negative electrode 21 and the positive electrode 22 expand during use of the storage element 1 having the same dimension in the Y-axis direction, the pressure in the Y-axis direction resulting from this expansion causes the edge 261 of the contact surface 260 of the second member 26 , 262, 263, and 264 can be suppressed.

  In the electrode body 2, neither the negative electrode 21 nor the positive electrode 22 may have the folded portion 23. Specifically, as shown in FIG. 15, the negative electrodes 21 extending in the Y-axis direction and the positive electrodes 22 extending in the Y-axis direction are alternately stacked so that the negative electrodes 21 are sandwiched between the adjacent positive electrodes 22 in the X-axis direction. May be Since the positions of the end edges 261 and 262 on one side of the contact surface 260 with the negative electrode 21 of the second member 26 and the end edges 263 and 264 on the other side of the contact surface 260 also differ according to this configuration, the second member 26 Even when the negative electrode 21 and the positive electrode 22 expand during use of the storage element 1 having the same dimension in the Y-axis direction, the pressure in the Y-axis direction resulting from this expansion causes the edge 261 of the contact surface 260 of the second member 26 , 262, 263, and 264 can be suppressed.

  Although the case where the storage element is used as a chargeable / dischargeable non-aqueous electrolyte secondary battery (for example, lithium ion secondary battery) has been described in the above embodiment, the type and size (capacity) of the storage element are arbitrary. . Moreover, in the said embodiment, although the lithium ion secondary battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the present invention can be applied to various secondary batteries, as well as storage devices of capacitors such as primary batteries and electric double layer capacitors.

  The storage element (for example, battery) 1 may be used for a storage device (battery module in the case of a storage element battery) 11 as shown in FIG. Power storage device 11 has at least two power storage elements 1 and a bus bar member 12 electrically connecting two (different) power storage elements 1 with each other. In this case, the technique of the present invention may be applied to at least one storage element 1.

  DESCRIPTION OF SYMBOLS 1 ... Storage element, 2 ... electrode body, 21 ... negative electrode (1st electrode), 21A ... mountain fold line, 21B ... valley fold line, 211 ... metal foil, 212 ... negative electrode active material layer, 22 ... positive electrode (2nd Electrodes) 221 metal foil 222 positive electrode active material layer 223 positive electrode main body 2230 central portion 2230S flat surface 2231 first end portion 2231S inclined surface 2232 second end portion 2232S: inclined surface, 224: positive electrode tab, 23: folded portion, 23A: first folded portion, 23B: second folded portion, 231, 231A, 231B: first surface, 232, 232A, 232B: second surface 233, 233A, 233B: flat portion, 2331: flat portion main body, 2332: negative electrode tab, 234, 234A, 234B: turn portion, 25: separator, 26: second member, 260: contact surface, 261, 262 263, 264 ... edge edge, 261 S, 262 S, 263 S, 234 S ... inclined surface, 3 ... case, 31 ... case main body, 310 ... opening peripheral part, 311 ... closed part, 312 ... body part, 313 ... long wall part, 314 ... Short wall portion 32 Lid plate 4 External terminal 6 Insulating member (contact member) 11 Power storage device 12 Busbar member 102 Electrode body 121 Negative electrode / separator crimp body 122 Positive electrode , 123: separator, 124: negative electrode body, R1, R2: virtual surface, C: central axis, θ1, θ2, θ3, θ4, θ5, θ6, θ7, θ8: inclination angle

Claims (5)

An electrode body having a first member including a first electrode, and a plurality of second members including a second electrode different in polarity from the first electrode;
The first member is sandwiched between the adjacent second members in a first direction,
The dimensions in the second direction orthogonal to the first direction of the adjacent second members are the same,
The position of the edge of one side in the second direction of the contact surface of the one second member of the adjacent second members with the first member, and the other of the adjacent second members A storage element, which is different in the second direction from the position of the one end of the contact surface of the second member with the first member. The edge of the one side of the contact surface of the one second member is located on the other side in the second direction than the edge of the one side of the contact surface of the other second member,
The one second member extends from the edge of the one side of the contact surface of the one second member to the one side, and the distance from an imaginary plane including the contact surface of the one second member Has a first inclined surface inclined so that the one side is larger,
The second electrode extends along the contact surface of the one second member, extends along at least a portion of the first inclined surface, and extends in the entire second direction in the second direction. The storage element according to claim 1, facing one electrode. The other second member extends from the edge of the one side of the other second member to the one side, and the distance from an imaginary plane including the contact surface of the other second member is the one side Have a second inclined surface inclined so as to be
The second electrode extends along the contact surface of the other second member, extends along at least a portion of the second inclined surface, and extends in the entire second direction in the second direction. The storage element according to claim 2 facing one electrode. An electrolytic solution,
And a case for containing the electrode body and the electrolytic solution,
The first member has a folded back portion turned at a turn portion so as to open the other side,
The one second member is sandwiched by the folded portion,
The end of the one side of the one second member is disposed inside the turn portion,
The other end of the one second member is disposed on the other side of the folded portion,
The one second member extends from the other side edge of the one second member to the other side, and the distance from the virtual surface including the contact surface of the other second member is the other side Have a third inclined surface inclined so as to be
The inclination of the first inclined surface with respect to the virtual surface including the contact surface of the one second member is the inclination of the third inclined surface with respect to the virtual surface including the contact surface of the one second member The storage element according to claim 2, which is more gradual. The first member has a pair of pinching portions pinching the one second member in the first direction, and a turn portion connecting the pair of pinching portions.
The end of the one side of the one second member is disposed inside the turn portion,
The one second member has a pair of the contact surfaces in contact with the pair of nipping portions, and has a pair of the first inclined surfaces extending respectively from the edge of the one side of the pair of contact surfaces. And
The storage element according to claim 2, wherein the second electrode in the one second member has a metal foil and a pair of active material layers sandwiching the metal foil in the first direction.