JP6951682B2 - Power storage element - Google Patents

Description

The present invention relates to a power storage element including 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. 19, this battery includes an electrode body 102 formed by combining a negative electrode / separator crimping body 121 and a positive electrode 122 and folding them in a bellows shape.

The negative electrode / separator crimping body 121 is configured by crimping a band-shaped negative electrode body 124 having a negative electrode as a base material between a pair of strip-shaped continuous separators 123, and is continuous in a band shape as a whole. The positive electrode 122 is configured by connecting a plurality of strip-shaped metal foils with positive electrode leads.

When manufacturing the electrode body 102, first, a band-shaped negative electrode body 124 is arranged between a pair of band-shaped separators 123, and these are crimped by a press or the like to form a negative electrode / separator crimping body 121. do. Further, the electrode body 102 is manufactured by forming a crease in the negative electrode / separator crimping body 121, inserting the positive electrode 122 into the negative electrode / separator crimping body 121, and then folding the positive electrode 122 along the crease.

By the way, in the battery provided with the electrode body 102, since there is no configuration around the positive electrode 122 that regulates the relative movement of the positive electrode 122 with respect to the negative electrode body 124 in the insertion direction, the negative electrode / separator crimping of the positive electrode 122 is performed. Relative movement to body 121 is not regulated. As a result, in the battery, the relative position between the positive electrode 122 and the negative electrode / separator crimping body 121 may deviate from the assumed position.

Japanese Unexamined Patent Publication No. 2013-222602

Therefore, the present embodiment is a power storage element in which a member including a second electrode is sandwiched in a folded portion of a member including a zigzag first electrode, and a member including the first electrode and a second member. It is an object of the present invention to provide a power storage element in which a member including an electrode is less likely to be displaced.

The power storage element of this embodiment is
A first folded portion that includes a first electrode and is folded back at a turn to open one side in the first direction, and a turn that is folded back to open the other side in the first direction. A long first member that is zigzag so that the second folded parts are arranged alternately,
A first second member including a second electrode having a polarity different from that of the first electrode and arranged inside the first folded portion, and a second electrode including the second electrode and the second folded portion. A plurality of second members including a second second member arranged inside,
Equipped with an electrode body with
The other end of the first second member comes into contact with the turn portion of the first folded portion.
The one-sided end of the second second member comes into contact with the turn portion of the second folded portion.

According to such a configuration, since the end portion of the second member is in contact with the turn portion of the first folded portion or the second folded portion, it is possible to prevent the second member from moving to the turn portion side. In other words, since the second member is positioned by the turn portion of the first folded portion or the second folded portion, the first member and the second member are less likely to be misaligned.

The second electrode includes a main body portion and a tab portion protruding from the main body portion in a second direction orthogonal to both the first direction and the direction in which the plurality of second members are arranged.
In the first direction
The distance from the other end edge of the first second member to the center of the tab portion is L1, and the distance from the one side edge of the second second member to the center of the tab portion. Is L2, the distance from the valley fold surface of the turn portion of the first folded portion to the valley fold surface of the turn portion of the second folded portion is L3, and the width of the tab portion is T1. You may satisfy the formula of.
L3> T1
L3-T1 <L1 + L2 <L3 + T1

In a configuration in which the end portion of the second member is in contact with the turn portion of the first folded portion or the second folded portion, the position of the end portion of the second member is determined by the position of the turn portion of the first member. Therefore, the end portion of the first second member and the end portion of the second second member do not always coincide with each other when viewed from the direction in which the plurality of second members are arranged. As a result, there arises a new problem that the tab portion of the first second member and the tab portion of the second second member may not overlap when viewed from the direction in which the plurality of second members are arranged. On the other hand, according to such a configuration, the distance based on the other end edge of the first second member (the edge abutting the turn portion of the first folded portion) and one of the second second members. Since the position of the tab portion is determined according to the distance with respect to the side edge (the edge that abuts the turn portion of the second folded portion), the first direction of the first and second second members. Regardless of the position of the end portion in, at least a part of the tab portion can be overlapped by the first and second second members.

In the power storage element,
The second electrode includes a plate-shaped main body portion and a tab portion protruding from the main body portion in a second direction orthogonal to both the first direction and the direction in which the plurality of second members are arranged.
Each of the plurality of second members has a separator that sandwiches the main body portion.
The shape of the first second member and the shape of the second second member are the same,
In the first direction
Let X be the distance between the valley fold surface of the turn portion of the first folded portion of the first member and the valley fold surface of the turn portion of the second folded portion of the first member, and the length of the separator. When the value is Y and the width of the tab portion is T1, the following formula may be satisfied.
2X> T1
X- (T1 / 2) <Y <X + (T1 / 2)

In a configuration in which the end portion of the second member is in contact with the turn portion of the first folded portion or the second folded portion, the position of the end portion of the second member is determined by the position of the turn portion of the first member. Therefore, the end portion of the first second member and the end portion of the second second member do not always coincide with each other when viewed from the direction in which the plurality of second members are arranged. As a result, there arises a new problem that the tab portion of the first second member and the tab portion of the second second member may not overlap when viewed from the direction in which the plurality of second members are arranged. On the other hand, according to such a configuration, the length of the separator in the first direction is adjusted according to the distance between the valley fold surfaces of the turn portion of the first folded portion and the second folded portion, so that the second has a different shape. The tab portion can be overlapped with the first and second second members without using the members.

The power storage element is
A case including the electrode body is provided.
Each of the plurality of second members is a separator including a bent portion, and can be used in either the separator sandwiching the second electrode and the direction in which the first direction and the plurality of second members are lined up from the separator. A tab portion that protrudes in a second direction orthogonal to each other and includes a tab portion that is a part of the second electrode.
In the second direction
The dimension from the end of the first second member on the side opposite to the side on which the tab portion protrudes to the position where the tab portion protrudes is the dimension of the tab on the separator of the second second member. It is the same as the dimension from the end on the side opposite to the protruding side to the position where the tab portion protrudes.
The amount of protrusion of the tab portion of the first second member is the same as the amount of protrusion of the tab portion of the second second member.
The valley fold surface of the bent portion covers the end portion of the main body portion of the second electrode opposite to the side on which the tab portion protrudes.
The electrode body may be arranged in the case in a state where the mountain fold surface of the bent portion of the separator is in direct or indirect contact with the inner surface of the case.

According to such a configuration, since the end portion on the side opposite to the protruding side of the tab portion of the separator is in contact with the inside of the case, the positions of the tab portion of the second electrode in the second direction can be aligned.

In the power storage element,
Each of the plurality of second members is a separator including a bent portion, and has a separator that sandwiches the second electrode.
In the first and second members
The other end of the second electrode abuts on the valley fold surface of the bent portion of the separator.
The mountain fold surface of the bent portion of the separator abuts on the turn portion of the first folded portion.
In the second second member
The one-sided end of the second electrode abuts on the valley fold surface of the bent portion of the separator.
The mountain fold surface of the bent portion of the separator may abut on the turn portion of the second folded portion.

According to this configuration, the mountain fold surface of the bent portion of the separator with the end portion of the second electrode abutted on the valley fold surface side abuts on the turn portion of the first folded portion or the second folded portion. The separator is less likely to shift to the turn side of the first member, and the second electrode is less likely to shift to the bent side of the separator. As a result, the second electrode is unlikely to be displaced toward the turn portion of the first member.

In the power storage element,
The second electrode includes a main body portion and a tab portion protruding from the main body portion in a second direction orthogonal to both the first direction and the direction in which the plurality of second members are arranged. In
The positions of the edges on the other side of the second electrode of the first second member and the second electrode of the second second member are different.
The shape of the second electrode in the second second member is the same as the inverted shape of the second electrode in the first second member.
In the first and second members
The tab portion is formed from the center of the other end edge of the second electrode in the first second member and the one side edge of the second electrode in the first second member. , It is shifted to the one side,
Let A be the amount of displacement of the tab portion, and the other end edge of the second electrode in the first second member and the other end of the second electrode in the second second member. When the distance to the edge is B and the width of the tab portion is T1, the following formula may be satisfied.
B> T1
(B / 2)-(T1 / 2) <A <(B / 2) + (T1 / 2)

According to such a configuration, the positions of the tab portions are overlapped by the second electrodes of the first and second second members without using the second electrodes having different shapes in the first and second second members. be able to.

According to the power storage element of the present embodiment, the power storage element in which the member including the second electrode is sandwiched in the folded portion of the member including the first electrode folded in a zigzag manner, and the member including the first electrode It is possible to provide a power storage element in which the member including the second electrode is less likely to be displaced.

FIG. 1 is a perspective view of a power storage element according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the power storage element. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. FIG. 4 is a perspective view for explaining the configuration of the electrode body. FIG. 5 is a schematic cross-sectional view for explaining the positional relationship between the first member and the second member. 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 negative electrode in the zigzag state. FIG. 8 is a perspective view for explaining a folded portion of the negative electrode. FIG. 9 is a diagram for explaining the configuration of the second member. FIG. 10 is a diagram for explaining the configuration of the second member. FIG. 11 is a schematic cross-sectional view for explaining the folded-back portion. FIG. 12 is a schematic view for explaining the folded-back portion and the positive electrode tab. FIG. 13 is a schematic view for explaining a folded-back portion and a positive electrode tab according to another embodiment. FIG. 14 is a schematic view for explaining a folded-back portion and a positive electrode tab according to another embodiment. FIG. 15 is a perspective view for explaining the configuration of the second member according to another embodiment. FIG. 16 is a perspective view for explaining the configuration of the second member according to another embodiment. FIG. 17 is a schematic view for explaining a folded-back portion and a positive electrode tab according to another embodiment. FIG. 18 is a perspective view of a power storage device including the power storage element. FIG. 19 is a cross-sectional view of a conventional power storage element.

Hereinafter, an embodiment of the power storage element according to the present invention will be described with reference to FIGS. 1 to 12. The power storage element includes a primary battery, a secondary battery, a capacitor, and the like. In the present embodiment, a rechargeable secondary battery will be described as an example of the power storage element. The name of each component (each component) of the present embodiment is that of the present embodiment, and may be different from the name of each component (each component) in the background technology.

The power storage element of this embodiment is a non-aqueous electrolyte secondary battery. More specifically, the power storage element is a lithium ion secondary battery that utilizes the electron transfer that occurs with the movement of lithium ions. This type of power storage element supplies electrical energy. The power storage element may be used alone or in combination of two or more. Specifically, the power storage element is used alone 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 power storage element is used in the power storage device in combination with another power storage element. In the power storage device, the power storage element used in the power storage device supplies electrical energy.

As shown in FIGS. 1 to 3, the power storage element includes an electrode body 2. Further, in the power storage element 1, the electrolytic solution, the case 3 containing the electrode body 2 and the electrolytic solution, the insulating member 4 arranged between the electrode body 2 and the case 3, and at least a part thereof are exposed to the outside. It also has an external terminal 5 and the like. In each figure, the configuration of the electrode body 2 is schematically shown by exaggerating the thickness of the electrodes and the like constituting the electrode body 2 in order to show the structure.

The electrolytic solution is a non-aqueous electrolyte solution. 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, and chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Electrolyte salts are LiClO ₄ , LiBF _{4 , LiPF 6} , and the like. _{The electrolytic solution of the present embodiment contains 1 mol / L LiPF 6} in a mixed solvent prepared by adjusting ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate in a ratio of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate = 3: 2: 5. Is dissolved.

As shown in FIGS. 4 and 5, the electrode body 2 has a first member 21 and a second member 22. The first member 21 includes a first electrode 210. The second member 22 includes a second electrode 220 having a polarity different from that of the first electrode 210.

The electrode body 2 of the present embodiment also has a separator 221 arranged between the first electrode 210 and the second electrode 220. Further, in the electrode body 2 of the present embodiment, the second member 22 includes a separator 221 in addition to the second electrode 220. Further, in the electrode body 2 of the present embodiment, the first member 21 is composed of the first electrode 210. In the electrode body 2 of the present embodiment, the first electrode 210 is a negative electrode and the second electrode 220 is a positive electrode.

As shown in FIGS. 6 and 7, the negative electrode 210 has a metal foil 211 and a negative electrode active material layer 212 stacked on both sides of the metal foil 211. That is, the negative electrode 210 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 210 has a long strip shape, and is zigzag so as to have a plurality of folded portions 23. Specifically, the negative electrode 210 opens the first folded portion 23A folded by the turn portion 234 so as to open one side in the first direction (long direction), and the other side in the long direction. The second folded portions 23B folded back at the turn portion 234 are zigzag folded so as to be alternately arranged (see FIG. 7).

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

The negative electrode active material is, for example, a carbon material such as graphite, non-graphitized carbon, and easily graphitized carbon, or a material that undergoes an alloying reaction with lithium ions such as silicon (Si) and tin (Sn). The negative electrode active material of this 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, polymethylmethacrylate, polyethylene oxide, polypropylene oxide, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid. Acid, styrene-butadiene rubber (SBR). The binder of this embodiment is polyvinylidene fluoride.

The negative electrode active material layer 212 may further have a conductive auxiliary agent such as Ketjen Black (registered trademark), acetylene black, and graphite. The negative electrode active material layer 212 of the present embodiment does not have a conductive auxiliary agent.

The first folded-back portion 23A has a valley fold surface 231 which is an inner surface and a mountain fold surface 232 which is an outer surface (a surface opposite to the valley fold surface 231), and the valley fold surfaces 231 face each other. A pair of flat portions 233 and a turn portion 234 connecting the ends of the pair of flat portions 233 are included. The second folded-back portion 23B also has the same configuration as the first folded-back portion 23A.

As shown in FIG. 11, the turn portion 234 is a region of the negative electrode 210 excluding the flat portion 233 (a portion outside the boundary α in FIG. 11). In the turn portion 234 of the present embodiment, both the mountain fold surface (outer peripheral surface) and the valley fold surface (inner peripheral surface) are located at the center of the flat portion in the X-axis direction and on both sides of the flat portion. It has a curved part.

In the negative electrode 210 of the present embodiment, the first folded portion 23A and the second folded portion 23B that are adjacent to each other with the turn portion 234 facing in the opposite direction are continuously folded in a state in which a part (flat portion 233) is shared. It is in a state (bellows-like). That is, in FIG. 7, when focusing on the first folded portion 23A, the first folded portion 23A and the second folded portion 23B adjacent to it (lower side in FIG. 7) are the turn portions of the first folded portion 23A. The flat portions 233A and 233B between the 234 and the turn portion 234 of the second folded portion 23B are shared.

Specifically, in the negative electrode 210, the flat portions 233 and the turn portions 234 are alternately formed by alternately folding the strip-shaped negative electrode 210 in the long direction at predetermined intervals. That is, the long negative electrode 210 alternately repeats mountain folds and valley folds 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. As a result, it becomes a spelled fold state. As a result, the negative electrode 210 has a plurality of flat portions 233 and a plurality of turn portions 234, each of the plurality of flat portions 233 is arranged in parallel or substantially parallel, and each of the plurality of turn portions 234 is adjacent to each other. The ends of the flat portion 233 on one end side in the elongated direction and the ends on the other end side are alternately connected to each other.

In the following, the direction in which the second members 22 are lined up is the X-axis direction in the Cartesian coordinate system, and the direction in which the turn portion 234 is arranged with respect to the flat portion 233 (the left-right direction in FIG. 5) is the Y-axis direction in the Cartesian coordinate system. (First direction), and the direction orthogonal to both the Y-axis direction and the direction in which the plurality of second members 22 are lined up (the fold (mountain fold line 21A, valley fold line 21B) direction of the negative electrode 210) is the Cartesian coordinate system. Z-axis direction (second direction).

As shown in FIGS. 7 and 8, each of the plurality of flat portions 233 protrudes from one side forming the rectangular flat portion main body 2331 and the rectangular contour of the flat portion main body 2331 (example of the present embodiment). The flat portion main body 2331 of the present embodiment has a rectangular shape that is long in the Y-axis direction. The flat portion main body 2331 has a metal foil. Both sides of the 211 are covered with the negative electrode active material layer 212, and the metal foil 211 is exposed on the negative electrode tab 2332. That is, the negative electrode tab 2332 does not have the negative electrode active material layer 212.

In the negative electrode 210 in the zigzag state, the negative electrode tabs 2332 of the flat portions 233 overlap each other when viewed from the X-axis direction. In the negative electrode 210 of the present embodiment, each negative electrode tab 2332 is from the end of the flat portion main body 2331 on one end in the Z-axis direction (upper side in FIG. 7) on the other side in the Y-axis direction (right side in FIG. 7). It extends in the Z-axis 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 5 via the current collector 6 (see FIG. 3). The bundle of the negative electrode tabs 2332 of the present embodiment is welded to the current collector 6.

In each of the plurality of turn portions 234, in the negative electrode 210 in the zigzag state, the strip-shaped negative electrode 210 is swiveled with the axis extending in the Z-axis direction as the folded shaft 234S (see FIG. 7) (in other words, along the folded shaft 234S). It is a part (folded back so that a crease is formed). Also in this turn portion 234, both sides of the metal foil 211 are covered with the negative electrode active material layer 212.

As shown in FIG. 11, the second member 22 includes a first second member 22A sandwiched between the first folded portions 23A and a second second member 22B sandwiched between the second folded portions 23B. including. In the second member 22 of the present embodiment, the positive electrode 220 included in the first second member 22A and the positive electrode 220 included in the second second member 22B are common in that their shapes are excluded.

As shown in FIGS. 9 and 10, the positive electrode 220 has a metal foil 222 and a positive electrode active material layer 223 that is laminated on both sides of the metal foil 222. That is, the positive electrode 220 has one metal foil 222 and a pair of positive electrode active material layers 223. The metal foil 222 of the present embodiment is, for example, an aluminum foil. The positive electrode 220 is arranged between the flat portions 233 adjacent to each other in the X-axis direction in the negative electrode 210 in the zigzag state while being covered with the separator 221. Specifically, the positive electrode 220 is sandwiched between the first folded portion 23A or the second folded portion 23B in a state of being covered with the separator 221. Therefore, the electrode body 2 of the present embodiment has a plurality of positive electrodes 220.

The positive electrode active material layer 223 has 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 , LiaMnzO _{4, LiaNixCoyMnzO 2,} etc.), LiaMeb ( XOc) d (Me represents one or more transition metals, X represents, for example, P, Si, B, V) polyanionic compounds (LiaFebPO ₄ , LiaMnbPO ₄ , LiaMnbSiO ₄ , LiaMnbPO ₄ F, etc.) ). The positive electrode active material of this embodiment is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .

The binder used for the positive electrode active material layer 223 is the same as the binder used for the negative electrode active material layer 212. The binder of this embodiment is polyvinylidene fluoride.

The positive electrode active material layer 223 may further have a conductive auxiliary agent such as Ketjen Black (registered trademark), acetylene black, and graphite. The positive electrode active material layer 223 of the present embodiment has acetylene black as a conductive auxiliary agent.

Specifically, each of the plurality of positive electrodes 220 extends in the Z-axis direction from the end edge in the Z-axis direction, which is one side forming the rectangular contour of the main body portion 224 and the main body portion 224 (in the example of the present embodiment). , A positive tab (tab portion) 225 extending in the Z-axis direction orthogonal to both the X-axis direction and the Y-axis direction. The main body portion 224 of the present embodiment has a rectangular shape and a plate shape that are long in the Y-axis direction. In the main body 224, both sides of the metal foil 222 are covered with the positive electrode active material layer 223, and in the positive electrode tab 225, the metal foil 222 is exposed. That is, the positive electrode tab 225 does not have the positive electrode active material layer 223.

The positive electrode active material layer 223 in the main body 224 faces the YZ plane (Y-axis and Z-axis) from the negative electrode active material layer 212 of the flat portion 233 facing in the X-axis direction (specifically, facing through the separator 221). Small in the (planar) direction including. That is, the positive electrode active material layer 223 of the main body portion 224 faces the negative electrode active material layer 212 of the flat portion 233 in the entire area, and the negative electrode active material layer 212 of the flat portion 233 is the main body portion 224 in the region excluding the peripheral portion. It faces the positive electrode active material layer 223. The dimension of the main body portion 224 in the Z-axis direction is, for example, 2 mm to 4 mm smaller than the dimension of the flat portion 233 of the negative electrode 210.

The positive electrode tabs 225 of each positive electrode 220 overlap when viewed from the X-axis direction. The positive electrode tab 225 of each positive electrode 220 of the present embodiment has a rectangular shape that is long in the X-axis direction (see FIGS. 9 and 10). Each positive electrode tab 225 has the same shape. Further, each of the positive electrode tabs 225 is opposite to the position of the negative electrode tab 2332 with respect to the flat portion main body 2331 on one side in the Y-axis direction at the end edge of the main body portion 224 in the Z-axis direction (upper side in FIG. 9). Side: Extends in the Z-axis direction from the end (left side in FIGS. 9 and 10). Further, both end edges of each positive electrode tab 225 in the Y-axis direction extend in the X-axis direction. The positive electrode tabs 225 extending from each of the plurality of main body portions 224 of the present embodiment are bundled and connected to the external terminal 5 via the current collector 6 (see FIG. 3). The bundle of positive electrode tabs 225 of this embodiment is welded to the current collector 6.

The positive electrode tab 225 of the present embodiment is Z from the first position on one edge of the main body 224 in the Z-axis direction or the second position on one edge of the main body 224 in the Z-axis direction. It extends in the axial direction. The distance from one end of the main body 224 at one end in the Z-axis direction to the first position is the second from the one end of the main body 224 at one end in the Z-axis direction. Different from the distance to the position.

The separator 221 is an insulating member and is arranged between the negative electrode 210 and the positive electrode 220. As a result, in the electrode body 2, the negative electrode 210 and the positive electrode 220 are insulated from each other. Further, the separator 221 holds the electrolytic solution in the case 3. As a result, when the power storage element 1 is charged and discharged, lithium ions can move between the negative electrode 210 and the positive electrode 220 facing each other with the separator 221 interposed therebetween.

The separator 221 is strip-shaped and is composed of, for example, a porous film such as polyethylene, polypropylene, cellulose, or polyamide. In the separator 221 of the present embodiment _{, an inorganic layer containing inorganic particles such as SiO 2} particles, Al ₂ O ₃ particles, and boehmite (alumina hydrate) is provided on a base material formed of a porous film. Is formed of. The base material of the separator 221 of the present embodiment is formed of, for example, polyethylene.

The separator 221 of the present embodiment covers the positive electrode 220 as described above. Specifically, the separator 221 covers the entire main body 224 so as to sandwich it in the X-axis direction. The separator 221 in a state where the positive electrode 220 is sandwiched is rectangular when viewed from the X-axis direction, the dimension in the Z-axis direction is larger than the dimension of the flat portion 233 of the negative electrode 210, and the dimension in the Y-axis direction is the flat portion. It is small compared to the size of 233. The separator 221 in a state of sandwiching the positive electrode 220 is the second member 22.

Further, the separator 221 of the present embodiment has a bent portion 2210. Specifically, the bent portion 2210 of the separator 221 is formed by bending a rectangular one at the central portion in the elongated direction so as to sandwich the positive electrode 220 between them. Further, in the separator 221 of the present embodiment, both end edges (two sides) in the fold direction are joined (adhesion, welding, etc.).

In the separator 221 in which the bent portion 2210 is arranged on the other side of the separator 221 of the present embodiment in the Y-axis direction, the end portion of the positive electrode 220 on the other side in the Y-axis direction is formed on the valley fold surface of the bent portion 2210 of the separator 221. 220A is in contact (see FIG. 9). Further, in the separator 221 of the separator 221 of the present embodiment in which the bent portion 2210 is arranged on one side in the Y-axis direction, the valley fold surface of the bent portion 2210 of the separator 221 is on one side of the positive electrode 220 in the Y-axis direction. The ends 220B are in contact (see FIG. 10).

The bent portion 2210 of the present embodiment is a region of the separator 221 excluding the flat portion. Further, as shown in FIG. 11, the mountain fold surface of the bent portion 2210 of the present embodiment has a flat portion located at the center in the X-axis direction and curved portions located on both sides of the flat portion. .. The valley fold surface of the bent portion 2210 is generally flat.

As shown in FIG. 4, the separator 221 of the present embodiment includes, in addition to the bent portion 2210, a first covering portion 2211 covering the front surface of the main body portion 224, and a second covering portion 2212 covering the back surface of the main body portion 224. And joined in a state where the parts extending from the first covering portion 2211 and the second covering portion 2212 to one side and located outside the one-sided edge 224B of the main body portion 224 are overlapped with each other. A second covering portion 2213, or a portion extending from the first covering portion 2211 and the second covering portion 2212 to the other side and located outside the other end edge 224A of the main body portion 224, in a state of being overlapped with each other. Also includes the second generation section 2214.

The first coating portion 2211 and the second coating portion 2212 of the separator 221 have a rectangular shape when viewed from the X-axis direction, and the dimensions in the Z-axis direction are substantially the same as the dimensions of the main body portion 224 of the positive electrode 220. The dimension in the Y-axis direction is larger than the dimension of the main body 224 of the positive electrode 220.

Further, in a state where the separator 221 sandwiches the positive electrode 220, the positive electrode tab 225 protrudes from the folded separator 221 and the both ends (two sides) of the separator 221 in the folding direction are joined while avoiding the positive electrode tab 225. It has been. Further, the dimensions of the first protrusion 2213 in the Y-axis direction and the dimensions of the second protrusion 2214 in the Y-axis direction are both larger than the thickness of the separator 221 (see FIG. 11). Further, since the positive electrode 220 contains the metal foil 222 and the separator 221 does not contain a metal material such as the metal foil 222, the positive electrode 220 is harder than the separator 221. In the electrode body 2 of the present embodiment, since both end edges (both end edges of the separator 221) are joined in a state where the separator 221 sandwiches the positive electrode 220, each second member 22 is relative to itself. The positive electrode 220 is included in a fixed position.

The dimension of the first protrusion 2213 in the Y-axis direction is the distance between both edges of the first protrusion 2213 in the Y-axis direction. The same applies to the dimensions of the second protrusion 2214 in the Y-axis direction.

In the electrode body 2 of the present embodiment, the other end 22C of the first second member 22A is in contact with the turn portion 234 of the first folded portion 23A in the Y-axis direction. Specifically, in the Y-axis direction, the mountain fold surface of the bent portion 2210 in which the other end 220A of the positive electrode 220 is in contact with the valley fold surface of the separator 221 is the turn portion 234 of the first folded portion 23A. It is in contact with the valley fold surface. Further, in the electrode body 2 of the present embodiment, the one-sided end portion 22D of the second second member 22B is in contact with the turn portion 234 of the second folded-back portion 23B. Specifically, in the Y-axis direction, the mountain fold surface of the bent portion 2210 in which one end 220B of the positive electrode 220 is in contact with the valley fold surface of the separator 221 is the turn portion 234 of the second folded portion 23B. It is in contact with the valley fold surface. In this way, the first second member 22A and the second second member 22B are in contact with the first folded portion 23A or the second folded portion 23B, and between the flat portions 233 adjacent to each other in the X-axis direction, respectively. The positive electrode 220 is in a state of facing each surface of the flat portion 233 of the negative electrode 210.

In the electrode body 2 of the present embodiment, the shape of the first second member 22A and the shape of the second second member 22B are the same. Therefore, the dimensions of each second member 22 of the present embodiment in the Y-axis direction are the same.

Further, in the electrode body 2 of the present embodiment, both end edges of the second member 22 in the Y-axis direction are the valley fold surface of the turn portion 234 of the first folded portion 23A and the turn portion 234 valley fold surface of the second folded portion 23B. It is located inside (the boundary α between the flat portion 233 and the turn portion 234 in the negative electrode 210). In other words, in the electrode body 2 of the present embodiment, the dimensions of the positive electrode 220 in the Y-axis direction are from the valley fold surface of the turn portion 234 of the first folded portion 23A to the valley fold surface of the turn portion 234 of the second folded portion 23B. Is smaller than the distance in the Y-axis direction.

Further, in the electrode body 2 of the present embodiment, as shown in FIG. 12, the distance from the other end edge 22E of the first second member 22A to the center 225C of the positive electrode tab 225 is L1 in the Y-axis direction. The distance from the one-sided edge 22F of the second second member 22B to the center 225C of the positive electrode tab 225 is L2, and the turn from the valley fold surface of the turn portion 234 of the first folding portion 23A to the turn of the second folding portion 23B. When the distance to the valley fold surface of the portion 234 is L3 and the width of the positive electrode tab 225 in the Y-axis direction is T1, the following formula is satisfied.
L3> T1
L3-T1 <L1 + L2 <L3 + T1

When the electrode body 2 satisfies the above formula, at least a part of the positive electrode tab 225 overlaps when viewed from the X-axis direction. In FIG. 12, in order to clarify the position of the positive electrode tab 225, the positive electrode tab 225 is painted in black.

Further, when the width of the joint portion of the positive electrode tab 225 in the Y-axis direction is T2, the entire joint portion of the positive electrode tab 225 is set to a size that overlaps with the positive electrode tab 225 in the Y-axis direction by satisfying the following formula. be able to.
L3> (T1-T2)
L3- (T1-T2) <L1 + L2 <L3 + (T1-T2)
The width T1 of the positive electrode tab 225 in the Y-axis direction is, for example, about 5 mm to 15 mm. The width T2 of the joint portion of the positive electrode tab 225 in the Y-axis direction is, for example, about 1 mm to 5 mm.

Specifically, in the electrode body 2 of the present embodiment, as shown in FIG. 12, the distance L1 from the other end edge 22E of the first second member 22A to the center 225C of the positive electrode tab 225 in the Y-axis direction. And the sum of the distance L2 from the one-sided edge 22F of the second second member 22B to the center 225C of the positive electrode tab 225 is the sum of the valley fold surface of the turn portion 234 of the first folding portion 23A to the second folding portion. It is equal to the distance L3 to the valley fold surface of the turn portion 234 of 23B. The phrase "the sum of L1 and L2 is equal to L3" includes the case where the sum of L1 and L2 is equal to L3 in consideration of the manufacturing error (within 0.5 mm). By configuring "the sum of L1 and L2 is equal to L3", the area where the plurality of positive electrode tabs 225 overlap each other can be maximized, so that the electrical resistance of the electrode body 2 can be reduced.

The mountain fold surface of the first second member 22A and the mountain fold surface of the second second member 22B of the present embodiment are the edge edges of the separator 221 and are located at the center in the X-axis direction as described above. It has a flat portion and curved portions located on both sides of the flat portion. Further, the distance L1 from the other end edge 22E of the first second member 22A to the center 225C of the positive electrode tab 225, and the one side edge 22F of the second second member 22B to the positive electrode The distance L2 from the center 225C of the tab 225 is the center 225C of the positive electrode tab 225 (positive electrode tab 225) from the flat portion located at the center of one end edge of the separator 221 or the one side edge of the separator 221. Is the distance to the center 225C) in the Y-axis direction.

The distance L1 from the other end edge 22E of the first second member 22A of the present embodiment to the center 225C of the positive electrode tab 225, and the one side edge 22F of the second second member 22B to the positive electrode. The distance L2 to the center 225C of the tab 225 is determined by changing the formation position of the positive electrode tab 225 in the Y-axis direction (specifically, from one end of the main body 224 in the Z-axis direction on one end). The distance to the first position where the positive electrode tab 225 is formed, and the distance from one end of the main body 224 on one end edge in the Z-axis direction to the second position where the positive electrode tab 225 is formed. , By making them different).

Further, the center of the positive electrode tab 225 of the present embodiment is the center of the positive electrode tab 225 with reference to both end edges in the Y-axis direction (centers at which the distances from both end edges in the Y-axis direction are equal).

Returning 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 this case 3, the internal space is defined by the case body 31 and the lid plate 32. The case 3 houses the electrolytic solution together with the electrode body 2 in this internal space. Therefore, the case 3 is formed of a metal that is resistant to the electrolytic solution. Case 3 of the present embodiment is formed of, for example, aluminum or an aluminum-based metal material such as an aluminum alloy.

The case body 31 includes a plate-shaped closing portion 311 and a cylindrical body portion (peripheral wall) 312 connected to the peripheral edge of the closing portion 311 (see FIG. 2).

The closing portion 311 is located at the lower end of the case main body 31 when the case main body 31 is arranged with the opening facing upward (that is, with the bottom wall portion of the case main body 31 when the opening faces upward). It is a part. The closed portion 311 of the present embodiment has a rectangular shape.

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 at the peripheral edge of the closed portion 311 and a pair of short wall portions 314 extending from the short side at the peripheral edge of the closed portion 311. A square cylindrical body portion 312 is formed by connecting the end portions of the short wall portion 314 corresponding to the pair of long wall portions 313 (specifically, facing each other in the X-axis direction).

As described above, the case body 31 has a square tube shape (that is, a bottomed square tube shape) in which one end in the opening direction (Z-axis direction) is closed. The case body 31 accommodates the electrode body 2 so that each flat portion 233 of the negative electrode 210 is parallel (substantially parallel) to the long wall portion 313 (that is, each turn portion 234 faces the short wall portion 314). Will be done.

The lid plate 32 is a member that closes the opening of the case body 31. The contour shape of the lid plate 32 is a shape corresponding to the opening peripheral edge portion 310 of the case main body 31. That is, the lid plate 32 is a rectangular plate material long in the X-axis direction.

The insulating member 4 covers at least a part of the electrode body 2. The insulating member 4 of the present embodiment is a non-porous sheet and is formed of an insulating resin. For example, the insulating member 4 is made of polyethylene, polystyrene, polyphenylene sulfide, or the like. Specifically, the insulating member 4 is formed in a bag shape in which the lid plate 32 side is opened by bending a sheet-shaped member having an insulating property cut into a predetermined shape.

Further, the insulating member 4 of the present embodiment is in the shape of a bag along the case body 31. In the bag-shaped insulating member 4, each flat portion 233 of the negative electrode 210 is substantially parallel to a portion (wall-shaped portion facing the X-axis direction) corresponding to the long wall portion 313 in the insulating member 4, and each turn portion 234. The electrode body 2 is housed so as to face a portion (a wall-shaped portion facing the Y-axis direction) corresponding to the short wall portion 314 of the insulating member 4. Since the insulating member 4 of the present embodiment has a bag shape with the lid plate 32 side open, when the electrode body 2 is housed, one end (upper side in FIG. 2) of the electrode body 2 in the Z-axis direction is held. It is in an open state.

The external terminal 5 is a portion electrically connected to an external terminal of another power storage element, an external device, or the like. Therefore, the external terminal 5 is formed of a conductive member. Further, the external terminal 5 is formed of a metal material having high weldability. For example, the external terminal 5 of the positive electrode is formed of an aluminum-based metal material such as aluminum or an aluminum alloy, and the external terminal 5 of the negative electrode is formed of a copper-based metal material such as copper or a copper alloy. The external terminal 5 of the present embodiment is attached to the lid plate 32 in a state where at least a part thereof is exposed to the outside of the case 3.

According to the above-mentioned power storage element 1, the end portion of the second member 22 (the other end portion 22C of the first second member 22A and the one side end portion 22D of the second second member 22B) is the second member. Since it is in contact with the turn portion 234 of the first folded portion 23A or the second folded portion 23B, it is possible to prevent the second member 22 from moving toward the turn portion 234. In other words, since the second member 22 is positioned by the turn portion 234 of the first folded portion 23A or the second folded portion 23B, the first member 21 and the second member 22 are unlikely to be misaligned.

Further, in the electrode body 2 of the present embodiment, since the position of the positive electrode tab 225 is determined with reference to the edge edges 22E and 22F of the second member 22 positioned with respect to the first member 21, the first first member. Regardless of the dimensions of the second member 22A in the Y-axis direction and the position of the end portion of the second second member 22B in the Y-axis direction, the positive electrode tab 225 is formed by the first second member 22A and the second second member 22B. At least part of each other can be overlapped.

More specifically, in a configuration in which the ends 22C and 22D of the second member 22 are in contact with the valley fold surface of the turn portion 234 of the first folded portion 23A or the second folded portion 23B, the turn of the first member 21 The positions of the ends 22C and 22D of the first second member 22A and the second second member 22B are determined by the position of the portion 234. Therefore, when viewed from the X-axis direction, the end portion 22C of the first second member 22A and the end portion 22D of the second second member 22B do not always match. As a result, there arises a new problem that the positive electrode tab 225 in the first second member 22A and the positive electrode tab 225 in the second second member 22B may not overlap when viewed from the X-axis direction. If the positive electrode tabs 225 do not overlap each other, it may not be possible to secure a sufficient area of the joint portion between the positive electrode tabs 225.

On the other hand, in the electrode body 2 of the present embodiment, the distance is based on the other end edge 22E of the first second member 22A (the end edge abutting the turn portion 234 of the first folded portion 23A). The position of the positive electrode tab 225 is determined according to the distance based on the one-sided edge 22F of the second second member 22B (the edge abutting the turn portion 234 of the second folded portion 23B). .. Specifically, in the Y-axis direction, the electrode body 2 has a distance from the other end edge 22E of the first second member 22A to the center 225C of the positive electrode tab 225 as L1, and the second second member 22B. The distance from the one-sided edge 22F to the center 225C of the positive electrode tab 225 is L2, from the valley fold surface of the turn portion 234 of the first folding portion 23A to the valley fold surface of the turn portion 234 of the second folding portion 23B. When the distance is L3 and the width of the positive electrode tab 225 in the Y-axis direction is T1, the following formula is satisfied (see FIG. 12).
L3> T1
L3-T1 <L1 + L2 <L3 + T1

As a result, regardless of the dimensions of the first second member 22A in the Y-axis direction and the dimensions of the second second member 22B in the Y-axis direction, the first second member 22A and the second second member 22B At least a part of the positive electrode tabs 225 can be overlapped with each other. The distance L3 from the valley fold surface of the turn portion 234 of the first folded portion 23A to the valley fold surface of the turn portion 234 of the second folded portion 23B is the valley fold surface of the turn portion 234 of the first folded portion 23A. It is the distance between the innermost point and the innermost point in the valley fold surface of the turn portion 234 of the second folding portion 23B.

Further, in the electrode body 2 of the present embodiment, the valley fold surface of the bent portion 2210 of the separator 221 positions the other end 220A or the one end 220B of the positive electrode 220 in the Y-axis direction. The misalignment between the negative electrode 210 and the positive electrode 220 can be suppressed.

More specifically, when the positive electrode 220 is sandwiched between the separators 221 and both ends of the second member 22 in the Y-axis direction are the first protrusion 2213 and the second protrusion 2214 of the separator 221. Even if the end portion of the second member 22 is brought into contact with the valley fold surface of the first folded portion 23A of the first member 21 or the turn portion 234 of the second folded portion 23B, positioning is difficult, and the negative electrode 210 and the positive electrode 220 are relative to each other. The position may shift. The reason why positioning is difficult is that the first protrusion 2213 and the second protrusion 2214 of the separator 221 do not include a hard part such as a metal material and are relatively soft, so that the turn portion 234 is brought into contact with the separator 221. This is because it is easy to bend when a force is applied toward the side.

On the other hand, in the electrode body 2, the mountain fold surface of the bent portion 2210 of the separator 221 in which the ends 220A and 220B of the positive electrode 220 are in contact with the valley fold surface in the Y-axis direction is the first folded portion 23A. Alternatively, in order to abut the valley fold surface of the turn portion 234 of the second folded portion 23B, the first protruding portion 2213 and the second protruding portion 2214 of the separator 221 are brought into contact with the turn portion of the first folded portion 23A or the second folded portion 23B. The positive electrode 220 and the negative electrode 210 are less likely to be misaligned than the configuration in which the valley fold surface of 234 is in contact with the fold surface.

Further, the periphery of the portion of the second member 22 that is in contact with the first member 21 (the valley fold surface of the turn portion 234 of the first folded portion 23A or the second folded portion 23B) is surrounded by the first member 21. Therefore, the electrolytic solution tends to be difficult to soak. On the other hand, in this configuration, the periphery of the portion of the second member 22 that is in contact with the first member 21 (the valley fold surface of the turn portion 234 of the first folded portion 23A or the second folded portion 23B) is the separator 221. Since it is possible to eliminate the need for joints between the two members, the electrolytic solution is more likely to permeate than when the parts where the two members are joined, such as the first protrusion 2213 and the second protrusion 2214, are in contact with each other. ..

The power 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 gist of the present invention. For example, the configuration of one embodiment can be added to the configuration of another embodiment, and a part of the configuration of one embodiment can be replaced with the configuration of another embodiment. In addition, some of the configurations of certain embodiments can be deleted.

As described above, in the configuration in which the ends 22C and 22D of the second member 22 are in contact with the valley fold surface of the turn portion 234 of the first folded portion 23A or the second folded portion 23B, the turn portion of the first member 21 The positions of the ends 22C and 22D of the first second member 22A and the second second member 22B are determined by the position of 234 (the position of the turn portion 234 of the first member 21 in the Y-axis direction). Therefore, when viewed from the X-axis direction, the one-sided end 22D of the first second member 22A and the one-sided end 22D of the second second member 22B do not always match. As a result, the positive electrode tab 225 in the first second member 22A and the positive electrode tab 225 in the second second member 22B may not overlap when viewed from the X-axis direction. On the other hand, in the power storage element 1 of the above embodiment, as shown in FIG. 12, by making the shape of the second member different (for example, the other end edge 22E of the first second member 22A). Although the shape of the positive electrode 220 is different depending on the reference distance and the distance based on the one end edge 22F of the second second member 22B), at least a part of the positive electrode tab 225 is overlapped. As shown in FIG. 13, the first protrusion 2213 or the second protrusion 2214 of the separator is brought into contact with the turn portion 234 on the valley fold surface side of the folded portion 23 of the first member 21, and the turn portion is formed. At least a part of the positive electrode tabs 225 may be overlapped with each other by adjusting the length of the first protruding portion 2213 or the second protruding portion 2214 of the separator 221 abutting on the 234 in the Y-axis direction. Also in FIG. 13, in order to clarify the position of the positive electrode tab 225, the positive electrode tab 225 is painted in black.

Specifically, since the shape of each positive electrode 220 is the same, each positive electrode tab 225 extends in the Z-axis direction from the same position in the Y-axis direction of one edge of each main body portion 224 in the Z-axis direction. You may be. Even if the dimension of each positive electrode 220 in the Y-axis direction is narrower than the distance in the Y-axis direction from the valley fold surface of the turn portion 234 of the first folded portion 23A to the valley fold surface of the turn portion 234 of the second folded portion 23B. good. Further, the distance from the other end edge 221C of the separator 221 in the first second member 22A to the positive electrode tab 225 (for example, from the other end edge 221C of the separator 221 in the first second member 22A to the positive electrode tab 225). Distance L4) to the center 225C of the The sum of the distance from the edge 221D to the center 225C of the positive electrode tab 225 is from the valley fold surface of the turn portion 234 of the first folding portion 23A to the valley fold surface of the turn portion 234 of the second folding portion 23B. The second protruding portion 2214 of the separator 221 abutting on the valley fold surface of the turn portion 234 of the first folded portion 23A so as to be equal to the distance X (second protruding portion 2214 of the first second member 22A). W2 in the Y-axis direction and the first protruding portion 2213 of the separator 221 (the first protruding portion of the second second member 22B) which is in contact with the valley fold surface of the turn portion 234 of the second folded portion 23B. 2213) may be adjusted with the dimension W1 in the Y-axis direction.

For example, the distance from the valley folding surface of the turn portion 234A of the first folded portion 23A to the edge 220C on the other end side of the positive electrode 220 of the first second member 22A is the valley of the turn portion 234B of the second folded portion 23B. When the distance from the folded surface to the edge 220D on one end side of the positive electrode 220 of the second second member 22B is equal, the dimension W1 of the first protrusion 2213 and the dimension W2 of the second protrusion 2214 are set. It should be equal. Further, the distance from the valley folding surface of the turn portion 234A of the first folded portion 23A to the edge 220C on the other end side of the positive electrode 220 of the first second member 22A is the valley of the turn portion 234B of the second folded portion 23B. When the distance from the folded surface to the edge 220D on one end side of the positive electrode 220 of the second second member 22B is larger than the distance, the dimension W2 of the second protrusion 2214 is first projected by the difference between these distances. It may be larger than the dimension W1 of the substitute portion 2213.

In this configuration, since the position of the positive electrode tab 225 is determined by adjusting the dimensions of the first protrusion 2213 and the second protrusion 2214 of the separator 221 in the Y-axis direction, the first second member 22A And the second second member 22B can align the positions of the positive electrode tabs 225 with each other.

Further, as shown in FIG. 14, the same shape is obtained by adjusting the distance between the valley fold surfaces of the turn portions 234 arranged on one side and the other side in the Y-axis direction and the length of the separator 221 in the Y-axis direction. At least a part of the positive electrode tabs 225 may be overlapped with each other while using the positive electrode 220 of the above. Also in FIG. 14, in order to clarify the position of the positive electrode tab 225, the positive electrode tab 225 is painted in black.

In this case, since the shape of each positive electrode 220 is the same, each positive electrode tab 225 extends in the Z-axis direction from the same position in the Y-axis direction of one end edge of each main body portion 224 in the Z-axis direction. May be good. Further, the distance between the valley fold surface of the turn portion 234A of the first folded portion 23A and the valley fold surface of the turn portion 234B of the second folded portion 23B) is defined as X, and the length of the separator 221 in the Y-axis direction is Y. And when the width of the positive electrode tab 225 is T1, the following formula may be satisfied.
2X> T1
X- (T1 / 2) <Y <X + (T1 / 2)

The distance X from the valley fold surface of the turn portion 234 of the first folded portion 23A to the valley fold surface of the turn portion 234 of the second folded portion 23B is the valley fold surface of the turn portion 234 of the first folded portion 23A. It is the distance between the innermost point and the innermost point in the valley fold surface of the turn portion 234 of the second folding portion 23B. The length Y of the separator 221 in the Y-axis direction is the distance between one end edge and the other end edge of the separator 221 in the Y-axis direction.

In this configuration, the length of the separator 221 in the Y-axis direction is adjusted according to the distance between the valley fold surfaces of the first folded portion 23A and the second folded portion 23B, so that the positive electrode 220 having a different shape is not used. At least a part of the positive electrode tabs 225 can be overlapped with each other by the first second member 22A and the second second member 22B.

Further, in this case, assuming that the width of the joint portion of the positive electrode tab 225 in the Y-axis direction is T2, the entire joint portion of the positive electrode tab 225 overlaps with the positive electrode tab 225 in the Y-axis direction by satisfying the following formula. Can be.
2X> (T1-T2)
X-{(T1-T2) / 2} <Y <X + {(T1-T2) / 2}

Further, in this case, by configuring "Y is equal to X", the area where the plurality of positive electrode tabs 225 overlap each other can be maximized, so that the electrical resistance of the electrode body 2 can be reduced. The phrase "Y is equal to X" includes the case where the value of Y in consideration of the manufacturing error (within 0.5 mm) is equal to X.

Further, the bent portion 2210 of the separator 221 may be in contact with the inside of the case 3.

Specifically, in the electrode body 2, as shown in FIG. 15, the valley fold surface of the bent portion 2210 of the separator 221 is the end portion 220F of the main body portion 224 of the positive electrode 220 opposite to the side on which the positive electrode tab 225 protrudes. May be covered.

In this case, as shown in FIG. 16, the position 2216 (for example, the positive electrode tab 225) in which the positive electrode tab 225 protrudes from the end portion 2215 on the side opposite to the side where the positive electrode tab 225 protrudes in the separator 221 of the first second member 22A (for example, the positive electrode tab 225). The dimension L6 in the Z-axis direction up to the protruding side edge 2216) is such that the positive electrode tab 225 protrudes from the end 2215 on the side opposite to the protruding side of the positive electrode tab 225 in the separator 221 of the second second member 22B. It may be the same as the dimension L6 in the Z-axis direction up to the position 2216. Further, in this case, the protrusion amount 225A of the positive electrode tab 225 of the first second member 22A (for example, the end of the separator 221 on the side opposite to the main body portion 224 of the positive electrode tab 225 from the edge 2216 on the side where the positive electrode tab 225 protrudes). The dimension in the Z-axis direction up to the edge 225B) may be the same as the protrusion amount 225A of the positive electrode tab 225 of the second second member 22B. In this case, the electrode body 2 may be arranged in the case 3 in a state where the mountain fold surface of the bent portion 2210 of the separator 221 is in direct or indirect contact with the inner surface of the case 3. Further, the end portion of the first member 21 in the Z-axis direction may also be arranged in the case 3 in a state of being in direct or indirect contact with the inner surface of the case 3.

In this electrode body 2, the end portion 2215 (bent portion 2210) on the side opposite to the protruding side of the positive electrode tab 225 of the separator 221 is in contact with the inside of the case 3, so that the Z axis of the positive electrode tab 225 of the positive electrode 220 is abutted. The position in the direction can be aligned.

Specifically, in the electrode body 2, even if the bent portion 2210 of the separator 221 covers the edge of the positive electrode 220 on the closed portion 331 side (lower edge in FIGS. 9, 10, etc.). good.

More specifically, when the positive electrode 220 is sandwiched between the separators 221 in the power storage element 1 in which the electrode body 2 and the electrolytic solution are housed in the case 3, the joints of both ends (two sides) of the separator 221 in the fold direction are joined. If there is a gap in the positive electrode 220 and this gap is located around the end portion of the positive electrode 220 on the closed portion 311 side of the case 3, the closed portion 311 of the case 3 and the positive electrode 220 pass through the gap of the separator 221. In some cases, the current was concentrated due to conduction.

On the other hand, in the electrode body 2, as shown in FIG. 14, the valley fold surface of the bent portion 2210 of the separator 221 has an end portion 220F located on the closed portion 331 side of the case 3 in the main body portion 224 of the positive electrode 220. You may cover it. In this case, the electrode body 2 may be arranged in the case 3 in a state where the mountain fold surface of the bent portion 2210 of the separator 221 is in contact with the closed portion 331 of the case 3.

In this electrode body 2, since the fold portion of the bent portion 2210 of the separator 221 is interposed between the closed portion 311 of the case 3 and the end portion 220F of the positive electrode 220, the periphery thereof (the closed portion 311 of the case 3 and the positive electrode) There is no joint portion of the separator 221 (around the periphery of the end 220F of 220). As a result, the conduction between the closed portion 311 of the case 3 and the positive electrode 220 is suppressed.

Further, as described above, in the configuration in which the ends 22C and 22D of the second member 22 are in contact with the valley fold surface of the turn portion 234 of the first folded portion 23A or the second folded portion 23B, the first member 21 The positions of the ends 22C and 22D of the first second member 22A and the second second member 22B are determined by the position of the turn portion 234. Therefore, when viewed from the X-axis direction, the end portion 22C of the first second member 22A and the end portion 22D of the second second member 22B do not always match. As a result, the positive electrode tab 225 in the first second member 22A and the positive electrode tab 225 in the second second member 22B may not overlap when viewed from the X-axis direction. On the other hand, in the power storage element 1 of the above-described embodiment, the positive electrode tabs 225 are stacked according to the configurations shown in FIGS. 12 and 13, but the positive electrode tabs 225 may be stacked according to another standard.

Specifically, as shown in FIG. 17, in the Y-axis direction, the positions of the positive electrode 220 of the first second member 22A and the positive electrode 220 of the second second member 22B are located on the other side of the edge 220C. Although different, the dimensions of the positive electrode 220 in the Y-axis direction are the same in each of the second members 22, and the positive electrode 220 has a valley fold surface of the turn portion 234 of the first folded portion 23A and a valley of the turn portion 234 of the second folded portion 23B. It may be arranged between the folded surface (inside the boundary α in FIG. 11). In this case, in the first second member 22A, the positive electrode tab 225 (for example, the center 225C of the positive electrode tab 225) is the other end edge 22E of the positive electrode 220 in the first second member 22A and the first second. The member 22A is deviated from the center 22G with the one-side end edge 220D of the positive electrode 220 to one side, and the amount of deviation of the positive electrode tab 225 is A, and the other end edge of the positive electrode 220 in the first second member 22A. When the distance between the 220C and the other end edge 220C of the positive electrode 220 in the second second member 22B is B and the width of the positive electrode tab 225 is T1, the following formula may be satisfied.
B> T1 (B / 2)-(T1 / 2) <A <(B / 2) + (T1 / 2)
Further, the shape of the positive electrode 220 in the second second member 22B may be the same as the shape obtained by reversing the shape of the positive electrode 220 in the first second member 22A. In other words, in the second second member 22B, the positive electrode tab 225 (for example, the center 225C of the positive electrode tab 225) is the one-sided edge 220D of the positive electrode 220 in the second second member 22B and the second second. The member 22B is displaced from the center 22H with the other end edge 220C of the positive electrode 220 to the other side, the amount of deviation of the positive electrode tab 225 is C, and the one end edge of the positive electrode 220 of the first second member 22A. The following formula may be satisfied when the distance between the 220D and the one-sided edge 220D of the positive electrode 220 in the second second member 22B is D and the width of the positive electrode tab 225 is T1.
D> T1
(D / 2)-(T1 / 2) <C <(D / 2) + (T / 2)
Also in FIG. 18, in order to clarify the position of the positive electrode tab 225, the positive electrode tab 225 is painted in black.

Further, assuming that the width of the joint portion of the positive electrode tab 225 in the Y-axis direction is T2, the entire joint portion of the positive electrode tab 225 is set to a size that overlaps with the positive electrode tab 225 in the Y-axis direction by satisfying the following formula. Can be done.
B> T1-T2
(B / 2)-{(T1-T2) / 2} <C <(B / 2) + {(T1-T2) / 2}

In this case, in the first second member 22A and the second second member 22B, the positive electrode 220 of the first second member 22A and the positive electrode of the second second member 22B are not used without using the positive electrodes 220 having different shapes. The positive electrode tab 225 can be stacked at 220.

Further, in this case, by configuring "C is equal to (B / 2)", the area where the plurality of positive electrode tabs 225 overlap can be maximized, so that the electrical resistance of the electrode body 2 can be reduced. Can be done. The phrase "C is equal to (B / 2)" includes the case where the value of C in consideration of the manufacturing error (within 0.5 mm) is equal to (B / 2).

The mountain fold surface and the valley fold surface of the turn portion 234 of the folded portion 23 of the above embodiment both have a flat portion located at the center in the X-axis direction and curved portions located on both sides of the flat portion. Although it had, at least one of the mountain fold surface and the valley fold surface may be curved as a whole. For example, when the valley fold surface of the turn portion 234 is curved as a whole, the distance from the valley fold surface of the turn portion 234 of the first folding portion 23A to the valley fold surface of the turn portion 234 of the second folding portion 23B is , The distance between the outermost point of the valley fold surface of the turn portion 234 of the first folding portion 23A and the outermost point of the valley fold surface of the turn portion 234 of the second folding portion 23B. You may.

Further, in FIGS. 12, 13, and 17 of the above embodiment, the position of the positive electrode tab 225 is determined by defining the center C of the positive electrode tab 225, but the position of the positive electrode tab 225 is set to the Y axis of the positive electrode tab 225. It may be determined by the edge in the direction or the like.

For example, instead of FIG. 12, in the Y-axis direction, the distance from the other end edge 22E of the first second member 22A to the other end edge of the positive electrode tab 225 and the second second member 22B. The sum of the distance from the edge 22F on one side to the edge on the other side of the positive tab 225, or from the edge 22E on the other side of the first second member 22A to the edge on one side of the positive tab 225. The sum of the distance between the two members and the distance from the one-sided edge 22F of the second second member 22B to the one-sided edge of the positive electrode tab 225, or the other edge of the first second member 22A. The distance from 22E to the other edge of the positive tab 225, the distance from one edge to the other edge of the positive tab 225, and the one-sided edge 22F of the second second member 22B. The sum of the distance from the positive value tab 225 to the other end edge of the positive electrode tab 225 is equal to the distance from the valley fold surface of the turn portion 234 of the first folded portion 23A to the valley fold surface of the turn portion 234 of the second folded portion 23B. You may.

For example, instead of FIG. 13, in the Y-axis direction, the distance from the other end edge 221C of the separator 221 in the first second member 22A to the other end edge of the positive electrode tab 225 and the second second. The sum of the distance from one end edge 221D of the separator 221 in the second member 22B to the other end edge of the positive electrode tab 225, or from the other end edge 221C of the separator 221 in the first second member 22A. The sum of the distance to one end edge of the positive electrode tab 225 and the distance from one end edge 221D of the separator 221 in the second second member 22B to one end edge of the positive electrode tab 225, or , The distance from the other end edge 221C of the separator 221 in the first second member 22A to the other end edge of the positive electrode tab 225, and from the one side edge to the other end edge of the positive electrode tab 225. Is the sum of the distance between The dimensions of the first second member 22A in the Y-axis direction and the second second member 22A so as to be equal to the distance from the folding surface to the valley folding surface of the turn portion 234 of the second folding portion 23B. (2) The dimensions of the first protrusion 2213 of the member 22B in the Y-axis direction may be determined.

For example, instead of FIG. 17, in the first second member 22A, one end edge of the positive electrode tab 225 or the other end edge is the other end edge 220C of the positive electrode 220 in the first second member 22A. From the center 22G with the one-sided edge 220D of the positive electrode 220 in the first second member 22A, in the other end 220C and the second second member 22B of the positive electrode 220 in the first second member 22A. The positive electrode 220 is deviated to one side by half the distance B from the other end edge 220C of the positive electrode 220, and in the second second member 22B, the one end edge or the other end edge of the positive electrode tab 225 is the second. From the center 22H of the one-sided edge 220D of the positive electrode 220 in the second second member 22B and the other end 220C of the positive electrode 220 in the second second member 22B, the positive electrode 220 in the first second member 22A. The distance D between the other end edge 220C and the other end edge 220C of the positive electrode 220 in the second second member 22B may be shifted to the other side by half.

Further, in the power storage element 1 of the above embodiment, the dimensions of the second member 22 in the Y-axis direction are the same, but they may be different. Further, in the power storage element 1 of the above embodiment, each end edge in the Y-axis direction of the second member 22 is located inside the boundary α between the flat portion 233 and the turn portion 234 of the negative electrode, but the second member 22 In the member 22, each end edge in the Y-axis direction may be located at the boundary α between the flat portion 233 and the turn portion 234 of the negative electrode, and each end edge in the Y-axis direction may be located at the flat portion 233 and the turn portion 234 of the negative electrode. It may be located outside the boundary α with. In other words, the dimension of the positive electrode 220 in the Y-axis direction is from the distance in the Y-axis direction from the turn portion 234 on the valley fold surface side of the first folding portion 23A to the turn portion 234 on the valley fold surface side of the second folding portion 23B. Although it was narrow, it may be the same as the distance in the Y-axis direction from the turn portion 234 on the valley fold surface side of the first folding portion 23A to the turn portion 234 on the valley fold surface side of the second folding portion 23B. It may be wider than this distance.

Further, although the positive electrode tab 225 of the above embodiment has a rectangular shape that is long in the X-axis direction, it may have another shape such as a rectangular shape or a square shape that is long in the Y-axis direction. Further, although the positive electrode tabs 225 of the above embodiment are joined at one place, they may be joined at a plurality of places. The area of each positive electrode tab 225 is preferably larger than that of the joint. Further, the positive electrode tabs 225 may be bundled by a clip or the like instead of being joined by welding or the like.

The separator 221 of the above embodiment includes the bent portion 2210, but does not include the bent portion 2210, for example, a sheet-like first member including the first covering portion 2211 and a sheet including the second covering portion 2212. It may have a structure formed by joining the second member of the shape. In this case as well, the separator 221 may include a first generation portion 2213 and a second generation portion 2214. Further, the separators 221 may not be joined to each other.

Further, the mountain fold surface of the bent portion 2210 of the above embodiment may be curved as a whole. In this case, the edge including the bent portion of the separator 221 may be a point located on the outermost side of the mountain fold surface of the bent portion 2210. Further, the valley fold surface of the bent portion 2210 of the above embodiment may be curved as a whole, and a flat portion located at the center in the X-axis direction and a curved portion located on both sides of the flat portion. And may have.

In the power storage element 1 of the above embodiment, the first member 21 is composed of the negative electrode 210 and the second member 22 is composed of the positive electrode 220 and the separator 221. However, even if the separator 221 is included in the first member 21. good. In this case, the separator 221 may have a zigzag shape similar to that of the negative electrode 210 (a zigzag shape having a plurality of folded portions). When the separator 25 is arranged along the long electrode, the separator 25 is included in the first member 21, and when the separator 25 is arranged along the rectangular electrode, the separator 25 is included. Is included in the second member 22.

Further, in the power storage element 1 of the above embodiment, the separator 221 in the state where the positive electrode 220 is sandwiched 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 210. , The dimension in the Y-axis direction was smaller than the dimension of the flat portion 233, but the dimension in the Z-axis direction may be substantially the same as or smaller than the dimension of the flat portion 233 of the negative electrode 210, and is in the Y-axis direction. The dimensions may be substantially the same as the dimensions of the flat portion 233.

Further, in the power storage element 1 of the above embodiment, the negative electrode 210 is in a zigzag state having a plurality of folded portions 23, and the positive electrode 220 is in a strip shape, but the configurations are opposite to each other, that is, the positive electrode 220 is a plurality of folded portions. It is in a zigzag state having 23, and the negative electrode 210 may be in the shape of a strip.

In the above embodiment, the case where the power storage element is used as a chargeable / dischargeable non-aqueous electrolyte secondary battery (for example, a lithium ion secondary battery) has been described, but the type and size (capacity) of the power storage element are arbitrary. .. Further, in the above embodiment, the lithium ion secondary battery has been described as an example of the power storage element, but the present invention is not limited to this. For example, the present invention can be applied to various secondary batteries, other primary batteries, and power storage elements of capacitors such as electric double layer capacitors.

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

1 ... power storage element, 2 ... electrode body, 21 ... first member, 21A ... mountain fold line, 21B ... valley fold line, 210 ... negative electrode (first electrode), 211 ... metal foil, 212 ... negative electrode active material layer, 22 ... 2nd member, 22A ... 1st second member, 22B ... 2nd second member, 22C, 22D ... end, 22E, 22F ... edge, 220 ... positive electrode (second electrode), 220A, 220B, 220F ... End, 220C, 220D ... Edge edge, 221 ... Separator, 2210 ... Bent part, 2211 ... First coating part, 2212 ... Second coating part, 2213 ... First generation part, 2214 ... Second output Substitute, 2215 ... end, 2216 ... position, 222 ... metal foil, 223 ... positive electrode active material layer, 224 ... main body, 224A, 224B ... edge edge, 225 ... positive electrode tab, 225A ... protrusion amount, 225C ... center, 225B ... Edge edge, 23 ... Folded part, 23A ... First folded part, 23B ... Second folded part, 231 ... Valley fold surface, 232 ... Mountain fold surface, 233, 233A, 233B ... Flat part, 2331 ... Flat part body , 2332 ... Negative electrode tab, 234 ... Turn part, 234S ... Folded shaft, 3 ... Case, 31 ... Case body, 310 ... Opening peripheral part, 311 ... Closure part, 312 ... Body part, 313 ... Long wall part, 314 ... Short wall Part, 32 ... lid plate, 4 ... insulating member, 5 ... external terminal, 6 ... current collector, 11 ... power storage device, 12 ... bus bar member, 102 ... electrode body, 121 ... negative electrode / separator crimping body, 122 ... positive electrode, 123 ... Separator, 124 ... Negative electrode body, α ... Boundary between flat part and turn part

Claims (3)

A first folded portion that includes a first electrode and is folded back at a turn to open one side in the first direction, and a turn that is folded back to open the other side in the first direction. A long first member that is zigzag so that the second folded parts are arranged alternately,
A first second member including a second electrode having a polarity different from that of the first electrode and arranged inside the first folded portion, and a second electrode including the second electrode and the second folded portion. A plurality of second members including a second second member arranged inside,
With an electrode body
A case including the electrode body and
With
The other end of the first second member comes into contact with the turn portion of the first folded portion.
End of the one side of the second of the second member is to abut against the turn portions of the second folded portion,
The second electrode includes a main body portion and a tab portion protruding from the main body portion in a second direction orthogonal to both the first direction and the direction in which the plurality of second members are arranged.
Each of the plurality of second members is a separator including a bent portion, and includes a separator that sandwiches the main body portion of the second electrode and a tab portion that protrudes from the separator in the second direction.
In the second direction
The dimension from the end of the first second member on the side opposite to the side on which the tab portion protrudes to the position where the tab portion protrudes is the dimension of the tab on the separator of the second second member. It is the same as the dimension from the end on the side opposite to the protruding side to the position where the tab portion protrudes.
The amount of protrusion of the tab portion of the first second member is the same as the amount of protrusion of the tab portion of the second second member.
The valley fold surface of the bent portion covers the end portion of the main body portion of the second electrode opposite to the side on which the tab portion protrudes.
The electrode body is a power storage element arranged in the case in a state where the mountain fold surface of the bent portion of the separator is in direct or indirect contact with the inner surface of the case. In the previous Symbol first direction,
The distance from the other end edge of the first second member to the center of the tab portion is L1, and the distance from the one side edge of the second second member to the center of the tab portion. Is L2, the distance from the valley fold surface of the turn portion of the first folded portion to the valley fold surface of the turn portion of the second folded portion is L3, and the width of the tab portion is T1. The power storage element according to claim 1, which satisfies the above formula.
L3> T1
L3-T1 <L1 + L2 <L3 + T1 A first folded portion that includes a first electrode and is folded back at a turn to open one side in the first direction, and a turn that is folded back to open the other side in the first direction. A long first member that is zigzag so that the second folded parts are arranged alternately,
A first second member including a second electrode having a polarity different from that of the first electrode and arranged inside the first folded portion, and a second electrode including the second electrode and the second folded portion. A plurality of second members including a second second member arranged inside,
Electrode body with
With
The other end of the first second member comes into contact with the turn portion of the first folded portion.
The one-sided end of the second second member comes into contact with the turn portion of the second folded portion.
Each of the plurality of second members is a separator including a bent portion, and has a separator that sandwiches the second electrode.
In the first and second members
The other end of the second electrode abuts on the valley fold surface of the bent portion of the separator.
The mountain fold surface of the bent portion of the separator abuts on the turn portion of the first folded portion.
In the second second member
The one-sided end of the second electrode abuts on the valley fold surface of the bent portion of the separator.
The mountain fold surface of the bent portion of the separator abuts on the turn portion of the second folded portion.
The second electrode includes a main body portion and a tab portion protruding from the main body portion in a second direction orthogonal to both the first direction and the direction in which the plurality of second members are arranged.
In the first direction
The positions of the edges on the other side of the second electrode of the first second member and the second electrode of the second second member are different.
The shape of the second electrode in the second second member is the same as the inverted shape of the second electrode in the first second member.
In the first and second members
The tab portion is formed from the center of the other end edge of the second electrode in the first second member and the one side edge of the second electrode in the first second member. , It is shifted to the one side,
Let A be the amount of displacement of the tab portion, and the other end edge of the second electrode in the first second member and the other end of the second electrode in the second second member. A power storage element that satisfies the following formula when the distance to the edge is B and the width of the tab portion is T1.
B> T1
(B / 2)-(T1 / 2) <A <(B / 2) + (T1 / 2)

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