JP2019096465A - Storage element - Google Patents

Abstract

To provide a storage element in which a current value of a current flowing at a short circuit point can be suppressed even if an internal short circuit occurs.SOLUTION: The storage element includes a plurality of electrode bodies 20 each having a first electrode 21 having a pair of flat portions facing each other and a turn portion connecting ends of the pair of flat portions and a second electrode 22 different in polarity from the first electrode 21 and disposed between the pair of flat portions. Each of the plurality of first electrodes 21 has a bonding portion 245 connecting the plurality of electrode bodies 20 to each other.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a storage element including an electrode body in which a second electrode is disposed inside a folded first electrode.

  Conventionally, a lithium ion secondary battery (hereinafter, simply referred to as "battery") in which one electrode plate of a negative electrode plate and a positive electrode plate is stacked in a zigzag manner is known (see Patent Document 1). Specifically, as shown in FIG. 12, this battery is configured by alternately laminating a negative electrode plate 501, a positive electrode plate 504, and separators 507 inserted between both electrode plates 501 and 504. Electrode stack.

  The negative electrode plate 501 is in close contact with the separator 507 on both sides, and is an electrode plate made of a long flexible material that is alternately folded at predetermined intervals in the longitudinal direction and stacked in a zigzag manner (a long electrode plate Is called). The long electrode plate 501 of the negative electrode has a negative electrode active material layer 503 formed on both sides of the copper foil 502.

  The separator 507 is made of a long insulating film, and is a battery separator capable of moving charges in the thickness direction. The separator 507 is folded in contact with both sides of the long electrode plate 501 of the negative electrode. Specifically, the separator 507 wraps the portion of the copper foil 502 of the long electrode plate 501 on which the negative electrode active material layer 503 is formed from both sides. That is, the long electrode plate 501 and the separator 507 which wraps the both surfaces thereof are integrated to form an integral long object 508.

  The positive electrode plate 504 is in close contact with the separator 507 on both sides, and is a large number of mutually independent strip-shaped electrode plates (referred to as strip-shaped electrode plates). Each strip-shaped electrode plate 504 of the positive electrode has a positive electrode active material layer 506 formed on both sides of the aluminum foil 505.

  A battery 500 is configured by alternately laminating a large number of strip-like electrode plates 504 on both sides of an integral long object 508 including the long electrode plate 501 and the separator 507. That is, when laminating one integral long material 508 and a large number of strip electrode plates 504, the integral long material 508 is folded in a zigzag manner, and the strip electrode plate 504 is inserted from both sides between them to form an integral long The battery 500 has a structure sandwiched by objects 508.

  When the negative electrode plate 501 and the positive electrode plate 504 short-circuit (internal short circuit) in the battery 500 due to an accident or the like of the device on which the battery 500 is mounted, a large current flows at the short-circuited portion, generating a large heat.

JP, 2014-103082, A

  So, this embodiment aims at providing the electrical storage element by which the electric current value of the electric current which flows in a short circuit location is suppressed, even if it carries out an internal short circuit.

The storage element of the present embodiment is
A first electrode having a pair of flat portions facing each other and a turn portion connecting ends of the pair of flat portions;
A plurality of electrode bodies having a polarity different from that of the first electrode and a second electrode disposed between the pair of flat portions,
Each of the plurality of first electrodes has a joint that connects the plurality of electrode bodies.

  As described above, by having a plurality of electrode bodies, the first electrode of each electrode body becomes smaller as compared with the configuration having only one electrode body, and each first electrode of a plurality of electrode bodies A resistance (contact resistance, etc.) caused by direct or indirect connection occurs at the junction, so a short circuit occurs between the flat portion (first electrode) and the second electrode in any electrode body. However, the current value of the current flowing at the short circuit point can be suppressed.

In the storage element,
A third electrode having the same polarity as the second electrode,
The plurality of electrode bodies are arranged in a direction in which the pair of flat portions face each other,
The third electrode may be disposed between adjacent electrode bodies.

  According to this configuration, the third electrode of the same polarity as the second electrode is disposed between the adjacent electrode bodies, so that it faces the counterpart member (the other electrode body) in each of the adjacent electrode bodies. The portion where the energy is stored can contribute to charge and discharge of the storage element, whereby the energy density of the storage element can be further improved.

Further, in the storage element,
And a current collecting member having conductivity,
The first electrode has an electrode body, and a current collection tab extending from the electrode body and constituting the junction.
The current collection tab may be connected to the current collection member in a non-contact state with the current collection tab of an electrode assembly different from the electrode assembly including the current collection tab.

  Thus, since the first electrodes of different electrode bodies conduct electricity indirectly via the current collection member, a plurality of contact resistances exist between the first electrodes of different electrode bodies. A configuration in which, even if a short circuit occurs between the flat portion (first electrode) and the second electrode, the first electrodes of different electrode bodies are directly conducted with each other by a current collection tab or the like (between the first electrodes Compared to the case where the contact resistance is one, the current value of the current flowing at the short circuit point is suppressed.

  As described above, according to the present embodiment, it is possible to provide a storage element in which the current value of the current flowing at the short-circuited portion can be suppressed even if the internal short circuit occurs.

FIG. 1 is a perspective view of a storage element according to the present embodiment. FIG. 2 is an exploded perspective view of the storage element. FIG. 3 is a cross-sectional view taken along line III-III of FIG. FIG. 4 is a perspective view for explaining an electrode group. FIG. 5 is a schematic cross-sectional view at the V-V position in FIG. 4. FIG. 6 is a diagram for explaining the negative electrode. FIG. 7 is a figure for demonstrating the structure of the negative electrode of a zigzag state. FIG. 8 is a perspective view for explaining the folded portion. FIG. 9 is a view for explaining a first strip-shaped member and a second strip-shaped member including a positive electrode and a separator. FIG. 10 is a schematic view showing the configuration of an electrode group according to another embodiment. FIG. 11 is a schematic view of a power storage device provided with the power storage element. FIG. 12 is a cross-sectional view schematically showing a laminated structure of a conventional battery.

  Hereinafter, an embodiment of a storage element according to the present invention will be described with reference to FIGS. 1 to 9. 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.

  The storage element includes an electrode group 2 as shown in FIGS. 1 to 3. The storage element 1 also includes a case 3 for housing the electrode group 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 group 2 and the external terminal 4. A body (current collecting member) 5 is provided. The storage element 1 also includes an insulating member 6 and the like disposed between the electrode group 2 and the case 3. In the drawings, in order to show the structure, the configuration of the electrode group 2 is schematically represented, such as exaggerating the thickness of the electrodes etc. constituting the electrode group 2.

  As shown also in FIG. 4, the electrode group 2 includes a plurality of electrode bodies 20 each having a first electrode 21 and a second electrode 22 different in polarity from the first electrode 21 (two in the example of the present embodiment) ) Equipped. The second electrode 22 of the present embodiment constitutes a first strip-shaped member 26. That is, the electrode body 20 includes the first electrode 21 and the first strip-shaped member 26 including the second electrode 22. In the electrode group 2 of the present embodiment, the first electrode 21 is a negative electrode, and the second electrode 22 is a positive electrode.

  The negative electrode 21 of each electrode body 20 has a metal foil 211 and a negative electrode active material layer 212 superimposed on each of both sides of the metal foil 211, as also shown in FIGS. 5 and 6. That is, each 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 has a long strip shape and has at least one folded portion 24. The details are as follows.

  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.

  The negative electrode 21 has a main body (electrode main body) 210 and a negative electrode tab (current collecting tab) 245 extending from the main body 210. More specifically, the negative electrode 21 has a direction (width) away from the long strip-shaped main body 210 folded in a zigzag state and the long side (end edge in the width direction (short direction)) 210A of the main body 210. And at least one negative tab 245 (see FIG. 6). As shown in FIGS. 7 and 8, the main body 210 of the present embodiment is a flat portion 243 having a substantially flat shape, and a turn portion that is curved (turned) around a pivot axis S extending in the width direction of the main body 210. By being arranged alternately with 244, it is in a zigzag state. In the main body 210, the folded back portion 24 is configured by a pair of flat portions 243 facing each other and a turn portion 244 connecting the ends of the pair of flat portions 243. The details are as follows.

  The folded back portion 24 has a first surface 241 which is a surface on the valley fold side and a second surface 242 which is a surface on the mountain fold side (that is, the surface opposite to the first surface 241) and It includes a pair of flat portions 243 in which one surface 241 faces each other, and a turn portion 244 connecting ends of the pair of flat portions 243. In the negative electrode 21 of the present embodiment, adjacent folded portions 24 (first folded portion 24A and second folded portion 24B described later) in a state in which the turn portion 244 is opposite to each other are partially (flat portions 243) Are in a continuous zigzag state (corrugated state) in a state in which

  In other words, in the negative electrode 21, the folded portion (first folded portion) 24 </ b> A folded so that one side in the predetermined direction (left and right direction in FIG. 7) is opened and the other side in the predetermined direction The folded-back portion (second folded-back portion) 24B folded back into a zigzag pattern is alternately disposed. Then, when focusing on one folded portion (first folded portion) 24A, the first folded portion 24A and the next (rear side in FIG. 7) folded portion (second folded portion) 24B Flat portions 243A and 243B between the first turn portion 244A which is the turn portion of the first folded portion 24A and the second turn portion 244B which is the turn portion of the second folded portion 24B. There is.

  In this case, as shown in FIG. 7, in the flat portion 243A when focusing on the first folded portion 24A, the surface on the valley folding surface side in the first folded portion 24A is the first surface 241A, and the opposite The side surface (the surface on the mountain fold side) is the second surface 242A. On the other hand, in the flat portion 243B (flat portion 243B common to the flat portion 243A of the first folded portion 24A) when focusing on the second folded portion 24B, the surface on the valley folded surface side in the second folded portion 24B Is the first surface 241B, and the opposite surface (the surface on the mountain fold side) is the second surface 242B. That is, in the flat portions 243A and 243B common to the first folded portion 24A and the second folded portion 24B, when focusing on the first folded portion 24A and focusing on the second folded portion 24B Then, the first surface (surface facing in the folded portion 24) 241 and the second surface (surface facing in the opposite direction in the folded portion) 242 are reversed.

  Specifically, as shown in FIG. 7, in each negative electrode 21, flat portions 243 and turn portions 244 are alternately formed by alternately turning back the strip-shaped main body 210 at predetermined intervals in the longitudinal direction. There is. That is, the long strip-shaped main body 210 alternately repeats the mountain fold and the valley fold at the position of the mountain fold line 21A and the position of the valley fold line 21B alternately set at predetermined intervals in the longitudinal direction shown in FIG. It becomes a zigzag state by being released. Thereby, the negative electrode 21 (main body 210) has a plurality of flat portions 243 and a plurality of turn portions 244, and each of the plurality of flat portions 243 is arranged in parallel or substantially in parallel. In each of the first turn portion 244A and the second turn portion 244B, the end portions on one end side and the end portions on the other end side of the flat portions 243 adjacent to each other are alternately connected. .

  Hereinafter, the direction in which the flat portions 243 are arranged is taken as the X axis direction in the orthogonal coordinate system, and the direction in which the turn portion 244 is arranged with respect to the flat portion 243 (horizontal direction in FIG. 7) is taken as the Y axis direction in the orthogonal coordinate system. The direction in which the pivot axis S of the turn portion 244 extends (see FIG. 7) is taken as the Z-axis direction in the orthogonal coordinate system.

  Each of the plurality of flat portions 243 has a rectangular shape as shown in FIG. 5, FIG. 7, and FIG. The flat portion 243 of the present embodiment has a rectangular shape elongated in the Y-axis direction. The entire area of both surfaces of the flat portion 243 is covered with the negative electrode active material layer 212.

  The negative electrode tab 245 protrudes from one side constituting the rectangular contour of the flat portion 243 (in the example of the present embodiment, it extends in the Z axis direction from the edge in the Z axis direction). The negative electrode tab 245 exposes the metal foil 211. That is, the negative electrode tab 245 is constituted only by the metal foil 211 and does not have the negative electrode active material layer 212.

  In the negative electrode 21 in the zigzag state, the negative electrode tabs 245 extending from the flat portions 243 overlap when viewed from the X-axis direction. In the negative electrode 21 of the present embodiment, each negative electrode tab 245 extends in the Z-axis direction from an end edge of one of the flat portions 243 in the Z-axis direction (upper side in FIG. 7). The negative electrode tabs 245 extending from each of the plurality of flat portions 243 are bundled and connected to the current collector 5 (see FIG. 3). Thereby, the bundle of the negative electrode tabs 245 is connected to the external terminal 4 through the current collector 5. The bundle of negative electrode tabs 245 of the present embodiment is connected to the current collector 5 by welding.

  In each of the plurality of turns 244, the strip-like main body 210 is pivoted (turned) with the axis extending in the Z-axis direction as the pivot axis S (see FIGS. 7 and 8) in the serpentine negative electrode 21. Then, it is a part curved around the pivot axis S). Also in the turn portion 244, both surfaces of the metal foil 211 are covered with the negative electrode active material layer 212. That is, in the turn portion 244, the negative electrode active material layer 212 is superimposed on the surface of the metal foil 211 facing the inner side (the first strip member 26 side) of the turn portion 244. Further, in the turn portion 244, the negative electrode active material layer 212 is also superimposed on the surface of the metal foil 211 facing outward (the surface facing the outside of the turn portion 244).

  As shown in FIG. 5, the first strip-shaped members 26 are disposed on the inner side of each folded portion 24 (specifically, between a pair of flat portions 243 constituting the folded portion 24). That is, the electrode body 20 of the present embodiment has a plurality of (the number corresponding to the number of the folding parts 24 of the negative electrode 21) the first strip-like members 26. Each of the plurality of first strip members 26 has a positive electrode 22 and a separator 28. In the electrode body 20 of the present embodiment, the configuration of all the first strip members 26 is the same.

  The positive electrode 22 has a metal foil 221 and a positive electrode active material layer 222 superimposed on each of both sides of the metal foil 221, as also shown in FIGS. 4 and 5. That is, the positive electrode 22 has one metal foil 221 and a pair of positive electrode active material layers 222. The metal foil 221 of the present embodiment is, for example, an aluminum foil. The positive electrode 22 is disposed between the pair of flat portions 243 of each folded portion 24 in the serpentine negative electrode 21. For this reason, the electrode body 20 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, as shown also in FIG. 9, 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) , And a positive electrode tab 224 extending in the Z-axis direction from an edge 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, the entire surface of the metal foil 221 is covered with the positive electrode active material layer 222, and in the positive electrode tab 224, the metal foil 221 is exposed. That is, the positive electrode tab 224 does not have the positive electrode active material layer 222.

  The positive electrode active material layer 222 in the positive electrode main body 223 is smaller in the Z-axis direction than the negative electrode active material layer 212 in the flat portion 243 facing in the X-axis direction (specifically, facing via the separator 28). In addition, 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 243 in the entire region.

  In the electrode body 20, the positive electrode tabs 224 of the respective positive electrodes 22 overlap when viewed from the X-axis direction. In the positive electrode 22 of the present embodiment, each positive electrode tab 224 is the other in the Y-axis direction (the position of the negative electrode tab 245 with respect to the positive electrode main body 223) at one end of the positive electrode body 223 in the Z axial direction (upper side in FIG. 4) Opposite side: It extends in the Z-axis direction from the end of FIG. 4). 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 through the current collector 5 (see FIG. 3). 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 245. The positive electrode tabs 224 of the positive electrode 22 disposed on different electrode bodies 20 (inside of the folded portions 24 of different negative electrodes 21) are also bundled together.

  The separator 28 is a member having an insulating property, and is disposed between the negative electrode 21 and the positive electrode 22. Thereby, in the electrode body 20, the negative electrode 21 and the positive electrode 22 are mutually insulated. Further, the separator 28 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 28.

The separator 28 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 28 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 28 of the present embodiment is formed of, for example, polyethylene.

  In the first strip-shaped member 26 of the present embodiment, the separator 28 covers the positive electrode 22. Specifically, the separator 28 covers the entire positive electrode main body 223 so as to sandwich it in the X-axis direction. As shown in FIGS. 4 and 9, the separator 28 is folded at the center in the longitudinal direction with the positive electrode 22 sandwiched between the rectangular ones, and the periphery (each edge) of the positive electrode 22 is joined. (Adhesion, welding, etc.) At this time, the positive electrode tab 224 protrudes from the folded back separator 28 (see FIG. 4), and the bonding is performed avoiding the positive electrode tab 224. The separator 28 in a state of sandwiching the positive electrode 22 has a rectangular shape as viewed from the X-axis direction.

  The plurality of electrode bodies 20 configured as described above are arranged in the X-axis direction (see FIG. 4). Thereby, all the flat parts 243 in each negative electrode 21 of a plurality of electrode bodies 20 are arranged in the X-axis direction in a mutually parallel or substantially parallel state.

  Further, the negative electrodes 21 of the plurality of electrode bodies 20 are electrically connected directly or indirectly at junctions (in the example of the present embodiment, the negative electrode tabs 245: see FIG. 3). Specifically, in the electrode group 2, the position of the negative electrode tab 245 in the Y-axis direction is different for each negative electrode 21 of each electrode body 20. Thereby, the negative electrode tab 245 is connected to the current collector 5 in a non-contact state with the negative electrode tab 245 of the electrode body 20 (negative electrode 21) different from the electrode body 20 (negative electrode 21) including the negative electrode tab 245. That is, the negative electrode tabs 245 of the negative electrodes 21 of different electrode bodies 20 are connected to the current collector 5 in a non-contact manner (see FIG. 3).

  The electrode group 2 of the present embodiment also includes a second strip-like member 27 including a third electrode 23. The polarity of the third electrode 23 is the same as the polarity of the second electrode 22, and the third electrode 23 of the present embodiment is a positive electrode.

  As shown in FIG. 4, the second strip-shaped members 27 are disposed between the electrode bodies 20 adjacent to each other in the X-axis direction (between the negative electrodes 21 in a zigzag state). The second strip-shaped member 27 of the present embodiment has the same configuration as the first strip-shaped member 26. That is, the second strip-shaped member 27 has the positive electrode 23 and the separator 28 as also shown in FIG. The positive electrode 23 has a metal foil and a positive electrode active material layer superimposed on each of both sides of the metal foil. The positive electrode 23 projects from a 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, the positive electrode extends from the edge in the Z-axis direction in the Z-axis direction) And a tab 224. Then, the separator 28 covers the whole of the positive electrode main body 223 of the positive electrode 23 so as to sandwich the whole in the X-axis direction, whereby the second strip-shaped member 27 is configured.

  Referring back to FIGS. 1 to 3, 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 group 2 in this internal space.

This electrolyte is a non-aqueous electrolyte. This 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 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 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.

  In the case 3 configured as described above, the plurality of electrode bodies 20 are bundled (laminated) in a state in which the second strip-like members 27 are sandwiched between the electrode bodies 20 adjacent to each other in the X-axis direction. Each flat portion 243 in the negative electrode 21 of each electrode body 20 is parallel (substantially parallel) to the long wall portion 313 (that is, the turn portion 244 in the negative electrode 21 of each electrode body 20 faces the short wall portion 314) The electrode group 2 in a state of being covered by the insulating member 6 is accommodated (see FIGS. 2 and 3). At this time, the first strip-shaped member 26 is disposed inside the folded portion 24 of the negative electrode 21 of each electrode body 20, and the case 3 presses (presses) the entire electrode group 2 in the X axis direction. The electrode group 2 is accommodated.

  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. Specifically, as shown in FIG. 2 and FIG. 3, the insulating member 6 is formed in a bag shape by bending a sheet-like member having insulation which is cut into a predetermined shape. The insulating member 6 of the present embodiment is shaped like a bag along the case 3.

  According to the storage element 1 described above, the electrode group 2 has the plurality of electrode bodies 20, and the negative electrodes 21 of the plurality of electrode bodies 20 are directly or indirectly in the junction (in the example of the present embodiment, the negative electrode tab 245). The negative electrode 21 of each electrode body 20 is more than the configuration in which the electrode group has only one electrode body (negative electrode) (the negative electrode 21 of the plurality of electrode bodies are integrally connected). It becomes small (short). Moreover, resistance (contact resistance etc.) resulting from each negative electrode 21 comrades of several electrode bodies 20 being directly or indirectly connected has arisen in the junction part. Therefore, even if a short circuit occurs between the negative electrode 21 (the negative electrode 21 of the folded portion 24) and the positive electrode 22 of the first strip-shaped member 26 in any of the plurality of electrode bodies 20, the current value of the current flowing at the shorted portion Is reduced.

  In the storage element 1 of the present embodiment, the second strip-shaped members 27 are disposed between the electrode bodies 20 (negative electrodes 21) adjacent in the X-axis direction. Thus, in the storage element 1, a second strip-like member including an electrode (positive electrode 23) of the same polarity as the electrode (positive electrode 22) of the first strip-like member 26 between adjacent electrode bodies 20 (negative electrode 21). By arranging 27, a portion of each of the adjacent electrode bodies 20 (negative electrode 21) facing the counterpart member (the other electrode body 20 (negative electrode 21)) can be made to contribute to charge and discharge of the storage element 1. it can. That is, a part of the negative electrode 21 of one of the negative electrodes 21 of the adjacent electrode assemblies 20 that faces the counterpart member (negative electrode 21 of the other electrode assembly) and a negative electrode of the other electrode assembly 20 Each of the portions facing the side member (the negative electrode 21 of the one electrode body 20) can contribute to the charge and discharge of the storage element 1. Thereby, the energy density of the storage element 1 can be further improved.

  Further, in the storage element 1 of the present embodiment, the negative electrode tab 245 of the negative electrode 21 in each electrode body 20 is the negative electrode tab 245 of the electrode body 20 (negative electrode 21) different from the electrode body 20 (negative electrode 21) including the negative electrode tab 245. And are connected to the current collector 5 in a non-contact state (see FIG. 3). As described above, since the negative electrodes 21 of different electrode bodies 20 conduct electricity indirectly via the current collector 5, a plurality of contact resistances (in the example of this embodiment) between the negative electrodes 21 of different electrode bodies 20. There are at least two contact resistances of the contact resistance between the negative electrode 21 of one electrode body 20 and the current collector 5 and the contact resistance between the negative electrode 21 of the other electrode body 20 and the current collector 5) It will be done. For this reason, even if a short circuit occurs between the negative electrode 21 (the negative electrode 21 of the folded portion 24) and the positive electrode 22 of the first strip-shaped member 26 in any of the plurality of electrode bodies 20, the negative electrode 21 of the different electrode body 20 The current value of the current flowing at the short-circuited point is suppressed as compared with the configuration in which the negative electrodes tab 245 and the like directly conduct (when the contact resistance between the negative electrodes 21 of different electrode bodies 20 is one).

  Further, in the storage element 1 of the present embodiment, the separators 28 surround the positive electrodes 22 and 23 in the strip-shaped members (the first strip-shaped member 26 and the second strip-shaped member 27). In other words, the entire positive electrode 22, 23 is enclosed by the separator 28. Therefore, even if heat generated by an internal short circuit or the like is applied to the strip-like members 26 and 27 and the separator 28 shrinks, etc., the internal positive electrodes 22 and 23 are hard to be exposed to the outside. Can prevent a new internal short circuit due to the exposure of the positive electrodes 22 and 23.

  In addition, in the storage element 1 of the present embodiment, the negative electrode 21 in each electrode body 20 is smaller (shorter) as compared with the case where the negative electrode is formed by winding one negative electrode in a zigzag manner. In this case, the number of folds (the number of turn portions 244) is reduced, which makes it difficult to cause stacking deviation and the like. For this reason, when bundling the some electrode body 20 containing the some negative electrode 21 of these zigzag-folded states and accommodating in case 3, it is easy to accommodate.

  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 group 2 of the above embodiment, the first strip-shaped member 26 and the second strip-shaped member 27 include the separator 28, but the present invention is not limited to this configuration. The negative electrode 21 may be sandwiched between the separators 28 in each electrode body 20. Specifically, for example, a long negative electrode 21 is stacked so as to be sandwiched by a pair of long separators 28, and a long member is formed. Then, the elongated members are folded in a serpentine state, and the positive electrodes 22 and 23 are disposed on the inner side of each folded portion and between the two elongated members in a folded state, whereby the electrode group 2 is configured.

  In the electrode group 2 of the embodiment, the negative electrode tab 245 is disposed at a different position in the Y-axis direction for each of the negative electrodes 21 of the plurality of electrode bodies 20, but the present invention is not limited to this configuration. In the negative electrode 21 of each electrode body 20, the negative electrode tab 245 may be disposed at the same position in the Y-axis direction. In this case, the negative electrode tabs 245 of the negative electrodes 21 of different electrode bodies 20 are bundled together and connected to the current collector 5. That is, the junctions where the negative electrodes 21 of the plurality of electrode bodies 20 are electrically connected may be configured such that the negative electrode tabs 245 of the different electrode bodies 20 (negative electrodes 21) are directly connected. Even with this configuration, the electrode group has only one negative electrode because there is contact resistance between the negative electrode tab 245 of the negative electrode 21 of one electrode body 20 and the negative electrode tab 245 of the negative electrode 21 of the other electrode body 20. Compared with the configuration (that is, the configuration in which the respective negative electrodes 21 of the plurality of electrode bodies 20 are continuous), the negative electrode 21 (the negative electrode 21 of one electrode body 20 of the plurality of electrode bodies 20) and the positive electrode 22 Even if a short circuit occurs between them, the current value of the current flowing at the short circuit point is suppressed.

  Moreover, in the electrode body 20 of the said embodiment, although one electrode (in the example of the said embodiment, the negative electrode 21) is a zigzag state, it is not limited to this structure. In the electrode body 20, one of the electrodes may have at least one folded portion 24. For example, as shown in FIG. 10, in each of the plurality of electrode bodies 20, the negative electrode 21 may have a configuration in which only one folded portion 24 is provided.

  Moreover, although the electrode group 2 of the said embodiment has two electrode bodies 20, you may have three or more electrode bodies 20. FIG. In this case, the second strip-like member 27 may be disposed between all the electrode bodies 20 or may be disposed between some of the electrode bodies 20. In addition, the electrode group 2 may have a configuration without the second strip-like member 27.

  In the electrode group 2 of the embodiment, the first electrode is the negative electrode 21, the second electrode is the positive electrode 22, and the third electrode is the positive electrode 23. However, the present invention is not limited to this configuration. The first electrode may be a positive electrode, and the second electrode and the third electrode may be a negative electrode.

  In the above embodiment, 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, the type and size (capacity) of the storage element are arbitrary. It is. 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 in a storage device (a battery module in the case of the storage element being a 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 group, 20 ... electrode body, 21 ... negative electrode (1st electrode), 21A ... mountain fold line, 21B ... valley fold line, 210 ... main body, 211 ... metal foil, 212 ... negative electrode active Material layer, 22: positive electrode (second electrode), 221: metal foil, 222: positive electrode active material layer, 223: positive electrode main body, 224: positive electrode tab, 23: positive electrode (third electrode), 24: folded portion, 24A: first folded portion, 24B: second folded portion, 241, 241A, 241B: first surface, 242, 242A, 242B: second surface, 243, 243A, 243B: flat portion, 244: turn Part, 244A: first turn part, 244B: second turn part, 245: negative electrode tab, 26: first strip-like member, 27: second strip-like member, 28: separator, 3: case, 31 ... case body, 310 ... opening peripheral portion, 11 blockade portion 312 body portion 313 long wall portion 314 short wall portion 32 lid plate 4 external terminal 5 current collector 6 insulating member 11 power storage device 12 bus bar Members, 500: battery, 501: negative electrode plate (long electrode plate), 502: copper foil, 503: negative electrode active material layer, 504: positive electrode plate (strip shaped electrode plate), 505: aluminum foil, 506: positive electrode Active material layer, 507 ... separator, 508 ... integral long object, S ... pivot

Claims (3)

A first electrode having a pair of flat portions facing each other and a turn portion connecting ends of the pair of flat portions;
A plurality of electrode bodies having a polarity different from that of the first electrode and a second electrode disposed between the pair of flat portions,
A storage element, wherein each of the plurality of first electrodes has a joint that connects the plurality of electrode bodies. A third electrode having the same polarity as the second electrode,
The plurality of electrode bodies are arranged in a direction in which the pair of flat portions face each other,
The storage element according to claim 1, wherein the third electrode is disposed between adjacent electrode bodies. And a current collecting member having conductivity,
The first electrode has an electrode body, and a current collection tab extending from the electrode body and constituting the junction.
The storage element according to claim 1, wherein the current collection tab is connected to the current collection member in a non-contact state with a current collection tab of an electrode body different from an electrode body including the current collection tab.