Power storage element

Abstract

The present invention comprises an electrode body that comprises a wound electrode plate. The electrode body comprises an electrode body body and a tab part. The tab part protrudes from the electrode body body at an end part in a first direction that is parallel to the winding axis of the electrode plate. The tab part comprises n tabs that are portions of the electrode plate that are stacked in a second direction that intersects the first direction (n being an integer that is at least 2). When T1, T2, … , Tn-1 are tab pitches that are the pitches between pairs of tabs that are adjacent in the extension direction of the electrode plate, Tp-1<Tp (p being an integer that is at least 2 and equal to or less than n), and Δ=T2-T1, TL>T1+(L-1)×Δ (n / 2<L≤n-1) and / or TS<T1+(S-1)×Δ (3≤S≤n / 2).

Description

Electric energy storage element

[0001] The present invention relates to an electric energy storage element.

[0002] Patent Document 1 discloses a battery including a wound electrode group. The wound electrode group forms an electrode group assembly by laminating a negative electrode, a positive electrode, and a separator in the order of negative electrode, separator, positive electrode, and separator, and winding the thus obtained electrode group assembly. In this wound electrode group, the pitch P between the negative electrode current collecting tab of the nth turn and the negative electrode current collecting tab of the (n + 1)th turn n is X a + 2πTα a equal to n, and the pitch P between the negative electrode current collecting tab of the (n + 1)th turn and the negative electrode current collecting tab of the (n + 2)th turn n+1 is X a + 2πTα a (n + 1). X a is an arbitrary constant, π is the ratio of a circle's circumference to its diameter, T is the thickness of the electrode group assembly, and α a is a correction constant.

[0003] Japanese Patent Application Laid-Open No. 2014-167890

[0004] In the wound electrode group included in the above conventional battery, the pitch P between the negative electrode current collecting tab of the nth turn and the negative electrode current collecting tab of the (n + 1)th turn n is represented by Xa + 2πTα a n. That is, the pitch P between two adjacent current collecting tabs n increases by a predetermined constant value (with 2πTα a ) every time n increases by 1. As a result, the positions of a plurality of negative electrode current collecting tabs are more likely to align than when the pitch P n is constant regardless of n. However, due to the fact that the shape of the curved portion of the electrode group assembly generated by winding is not constant, etc., when the pitch P n is determined using the above formula, there is a problem that the positions of a plurality of negative electrode current collecting tabs cannot be sufficiently aligned. The misalignment of tabs such as negative electrode current collecting tabs causes factors such as poor bonding between the tab and the conductive member.

[0005] This invention was made by the present inventors by newly focusing on the above-mentioned problems, and aims to provide an energy storage element with improved reliability.

[0006] An energy storage element according to one aspect of the present invention comprises an electrode body having a wound electrode plate, the electrode body comprising an electrode body body and a tab portion, the tab portion protruding from the end of the electrode body body in a first direction parallel to the winding axis of the electrode plate, the tab portion comprising n tabs (where n is an integer of 2 or more) which are part of the electrode plate and are stacked in a second direction intersecting the first direction, and the tab pitch, which is the pitch between two adjacent tabs in the direction in which the electrode plate extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let L be at least one integer satisfying n / 2 < L ≤ n-1, then T Ｌ >T １ It satisfies + (L-1) × Δ.

[0007] Another embodiment of the present invention provides an electrode body comprising a wound electrode plate, the electrode body comprising an electrode body body and a tab portion, the tab portion protruding from the end of the electrode body body in a first direction parallel to the winding axis of the electrode plate, the tab portion comprising n tabs (where n is an integer of 2 or more) which are part of the electrode plate and are stacked in a second direction intersecting the first direction, and the tab pitch, which is the pitch between two adjacent tabs in the direction in which the electrode plate extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let S be at least one integer satisfying 3 ≤ S ≤ n / 2, then T Ｓ <T １ It satisfies + (S-1) × Δ.

[0008] According to the present invention, it is possible to provide an energy storage element with improved reliability.

[0009] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. Figure 2 is an exploded perspective view of an energy storage element according to an embodiment. Figure 3 is a perspective view showing the configuration of an electrode body according to an embodiment. Figure 4 is a schematic cross-sectional view showing the configuration of a laminate according to an embodiment. Figure 5 is a schematic top view showing the configuration of an electrode body according to an embodiment. Figure 6 is a schematic top view showing the configuration of a tab portion according to an embodiment. Figure 7 is a schematic diagram showing the positions of multiple tabs on an electrode plate according to an embodiment. Figure 8A is a schematic top view showing the configuration of a tab portion in a comparative example. Figure 8B is a diagram showing a model example for calculating the tab pitch. Figure 9A is a schematic diagram showing the first curved shape of an electrode plate in a comparative example. Figure 9B is a schematic diagram showing the second curved shape of an electrode plate in a comparative example. Figure 9C is a schematic diagram showing the third curved shape of an electrode plate in a comparative example. Figure 10 is a schematic diagram showing the change in tab pitch in an electrode body according to an embodiment. Figure 11 is a schematic plan view showing the configuration of a modified energy storage device according to the embodiment.

[0010] (1) An energy storage element according to one aspect of the present invention comprises an electrode body having a wound electrode plate, the electrode body comprising an electrode body body and a tab portion, the tab portion protruding from the end of the electrode body body in a first direction parallel to the winding axis of the electrode plate, the tab portion comprising n tabs (n is an integer of 2 or more) which are part of the electrode plate and are stacked in a second direction intersecting the first direction, and the tab pitch, which is the pitch between two adjacent tabs in the direction in which the electrode plate extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let L be at least one integer satisfying n / 2 < L ≤ n-1, then T Ｌ >T １ It satisfies + (L-1) × Δ.

[0011] In the curved portions at both ends of a wound electrode body, the electrode plate in the portion closest to the outermost circumference (hereinafter also referred to as the "outer circumference") tends to bulge outward more than the assumed semi-circular shape. As a result, the tabs in the outer circumference, that is, the tabs in the range close to the end of the winding of the electrode plate (hereinafter also referred to as the "starting end") in the direction in which the electrode plate extends, tend to shift in the direction toward the starting end of the winding in the direction in which the electrode plate extends. In relation to this problem, in an energy storage element according to one aspect of the present invention, at least one tab pitch T in the outer circumference of the electrode body Ｌ (n / 2 < L ≤ n-1) is defined as the reference pitch difference Δ and the tab pitch T. Ｌ The tab pitch is made larger than the product of the number of tabs up to (L-1). This allows for a relatively long tab pitch T, taking into account that the electrode plate will bulge outwards. Ｌ This is achieved. As a result, the multiple tabs stacked in the second direction become more easily aligned in the direction in which the electrode plate extends. This allows for good bonding between the tab portion and conductive members such as current collectors. Thus, the energy storage element according to this embodiment is an energy storage element with improved reliability.

[0012] (2) In the energy storage element described in (1) above, for all L that satisfy 2n / 3 < L ≤ n-1, T Ｌ >T １ It may also be stated that it satisfies + (L-1) × Δ.

[0013] According to the energy storage element described in (2) above, there are multiple tab pitches T near the end of the electrode plate. Ｌ All of the integers L (where n² / 3 < L ≤ n-1) are relatively long values ​​that take into account the outward bulge of the electrode plates in the curved sections. As a result, the positions of the electrode plates of the multiple tabs stacked in the second direction become more aligned in the direction of extension.

[0014] (3) In the energy storage element described in (1) or (2) above, further, T Ｌ－１ -T Ｌ－２ <T Ｌ -T Ｌ－１ It may also be stated that it satisfies the following conditions.

[0015] According to the energy storage element described in (3) above, the tab pitches of at least three consecutive tabs near the end of the electrode plate are determined such that the difference in tab pitch increases as it approaches the end of the electrode plate. As a result, the accumulation of the outward bulge of the electrode plate at the outer circumference of the electrode body is reflected in these at least three tab pitches. Consequently, the positions of the multiple tabs stacked in the second direction in the direction in which the electrode plate extends become more easily aligned.

[0016] (4) Another embodiment of the present invention provides an electrode body comprising a wound electrode plate, the electrode body comprising an electrode body body and a tab portion, the tab portion protruding from the end of the electrode body body in a first direction parallel to the winding axis of the electrode plate, the tab portion comprising n tabs (n is an integer of 2 or more) which are part of the electrode plate and are stacked in a second direction intersecting the first direction, and the tab pitch, which is the pitch between two adjacent tabs in the direction in which the electrode plate extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let S be at least one integer satisfying 3 ≤ S ≤ n / 2, then T Ｓ <T １ It satisfies + (S-1) × Δ.

[0017] In the curved portions at both ends of a wound electrode body, the inner circumferential electrode plate tends to have a substantially bent shape that passes inward from the assumed semi-circular arc shape. As a result, the inner tabs, i.e., the tabs in the range close to the starting end in the direction in which the electrode plate extends, tend to shift away from the starting end in the direction in which the electrode plate extends. In relation to this problem, in an energy storage element according to another aspect of the present invention, at least one tab pitch T included in the inner circumferential portion of the electrode plate Ｓ (3 ≤ S < n / 2) is defined as the reference pitch difference Δ and the tab pitch T. Ｌ The tab pitch is made smaller than the product of the number of tabs up to (L-1). This takes into account that the electrode plate will have a roughly bent shape in the curved section, resulting in a relatively short tab pitch T. ＬThis is achieved. As a result, the multiple tabs stacked in the second direction become more easily aligned in the direction in which the electrode plate extends. This allows for good bonding between the tab portion and conductive members such as current collectors. Thus, the energy storage element according to this embodiment is an energy storage element with improved reliability.

[0018] (5) In the energy storage element described in (4) above, for all S that satisfy 3 ≤ S ≤ n / 3, T Ｓ <T １ It may also be stated that the condition + (S-1) × Δ is satisfied.

[0019] According to the energy storage element described in (5) above, there are multiple tab pitches T near the beginning of the winding of the electrode plate. Ｓ (S is all integers satisfying n / 3 < S ≤ n-1) is a relatively short value, taking into account that the electrode plate takes on a roughly bent shape in the curved section. As a result, the positions of the electrode plates of the multiple tabs stacked in the second direction become even more aligned in the direction in which they extend.

[0020] The following description of an energy storage element according to an embodiment (including its modifications) of the present invention will be given with reference to the drawings. Note that the embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit the present invention. Furthermore, dimensions and other specifications in each figure are not strictly illustrated. Additionally, the same or similar components are denoted by the same reference numerals in each figure.

[0021] In the following description and drawings, the direction of alignment of a pair of terminals on an energy storage element, the direction of alignment of a pair of current collectors, or the direction of alignment of a pair of short sides on a single container is defined as the X-axis direction. The direction of alignment of a pair of long sides on a single container, the direction of stacking of electrode plates in the middle of the electrode body, or the thickness direction of the container is defined as the Y-axis direction. The direction of alignment of the container body and lid of the energy storage element, or the longitudinal direction of the short side of the container is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Depending on the usage, the Z-axis direction may not be vertical, but for the sake of explanation below, the Z-axis direction will be described as vertical.

[0022] In the following explanation, for example, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. When simply referring to the X-axis direction, it refers to either the X-axis positive direction or the X-axis negative direction, or either direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. For example, two directions being parallel means not only that the two directions are perfectly parallel, but also that they are substantially parallel, i.e., that they may have a difference of, for example, a few percent. Furthermore, in the following explanation, when the term "insulation" is used, it means "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶ ６ Preferably Ωm or more, 1 × 10 ７ Ωm or greater is more preferable, 1 × 10 １０ A value of Ωm or greater is even more preferable.

[0023] (Embodiment) [1. General Description of the Energy Storage Element 10] First, a general description of the energy storage element 10 in this embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to the embodiment. Figure 2 is an exploded perspective view of the energy storage element 10 according to the embodiment.

[0024] The energy storage element 10 is a secondary battery, more specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 can be used, for example, as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), aircraft, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0025] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may also be a primary battery.

[0026] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of terminals 200, and a pair of external insulating members 300. As shown in Figure 2, the container 100 houses an electrode body 700, a pair of current collectors 500, and a pair of internal insulating members 400. The container 100 contains a non-aqueous electrolyte, which is an electrolyte solution, but is not shown in the illustration. There are no particular restrictions on the type of electrolyte solution, as long as it does not impair the performance of the energy storage element 10, and various types can be selected. Furthermore, spacers and insulating films, etc., which are not shown, may be placed inside the container 100.

[0027] The container 100 is a rectangular parallelepiped (box-shaped) case. A rectangular parallelepiped, as used here, is a hexahedron whose faces are all rectangles or squares. The container 100 has a container body 110 and a lid 120 that closes the opening of the container body 110. After the electrode body 700 is placed inside the container body 110, the inside of the container 100 is sealed by welding the container body 110 and the lid 120 together. The material of the container body 110 and the lid 120 is not particularly limited, but it is preferable that they be weldable metals such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0028] The container body 110 is a rectangular cylindrical member with a bottom and an opening at the top. The container body 110 has a pair of short sides 112 aligned in the X-axis direction, a pair of long sides 113 aligned in the Y-axis direction, and a bottom surface 114 in the negative Z-axis direction. The lid 120 is a rectangular plate-like member that closes the opening of the container body 110. The lid 120 is equipped with a gas discharge valve 122 that discharges gas from inside the container 100 when the internal pressure of the container 100 rises excessively. The lid 120 may also be provided with an injection port or the like for injecting electrolyte into the container 100.

[0029] The electrode body 700 is an energy storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator, and is capable of storing electricity. The electrode body 700 includes an electrode body main body 710 and a pair of tab portions 730 provided on one side of the electrode body main body 710 in the Z-axis direction. The tab portion 730 is a part also called, for example, a "current collection portion" or "connection portion," and comprises a plurality of stacked tabs 720. Hereinafter, when distinguishing between the positive electrode tab portion 730 and the negative electrode tab portion 730, the negative electrode tab portion 730 will be referred to as tab portion 730A, and the positive electrode tab portion 730 will be referred to as tab portion 730B. When distinguishing between the positive electrode tab 720 and the negative electrode tab 720, the negative electrode tab 720 will be referred to as tab 720a, and the positive electrode tab 720 will be referred to as tab 720b. Details of the configuration of the electrode body 700 will be described later with reference to Figures 3 to 5.

[0030] In this embodiment, a current collector 500 is joined to each of the pair of tab portions 730, as shown in Figure 2. For example, the tab portion 730 is bent so that its tip faces the positive Y-axis direction, and the tab portion 730 is joined to the Z-axis negative surface of the current collector 500. As a method for joining the current collector 500 and the tab portion 730, for example, ultrasonic bonding is used. There are no particular limitations on the joining method, and laser welding, resistance welding, or crimping may also be used as the joining method.

[0031] The terminal 200 is a component that is electrically connected to the electrode body 700 via the current collector 500. Specifically, one end of the pair of terminals 200 is electrically connected to the positive electrode plate of the electrode body 700, and the other end of the pair of terminals 200 is electrically connected to the negative electrode plate of the electrode body 700. The terminal 200 is attached to a cover 120 positioned above the electrode body 700. Specifically, the terminal 200 has a shaft portion 201 that penetrates the cover 120. The shaft portion 201 of the terminal 200 is inserted into and crimped through the through hole 301 of the external insulating member 300, the through hole 123 of the cover 120, the through hole 401 of the internal insulating member 400, and the through hole 501 of the current collector 500. In this way, the terminal 200 is fixed to the cover 120 together with the external insulating member 300, the internal insulating member 400, and the current collector 500. The terminal 200 is made of aluminum, aluminum alloy, copper, or copper alloy.

[0032] The external insulating member 300 is a member that insulates the cover 120 from the terminal 200. In this embodiment, the external insulating member 300 also functions as a gasket that seals the space between the cover 120 and the shaft portion 201 of the terminal 200. The internal insulating member 400 is a member that insulates the cover 120 from the current collector 500. Both the external insulating member 300 and the internal insulating member 400 are formed from a resin material that has electrical insulating properties.

[0033] The current collector 500 is a flat plate-shaped member that electrically connects the electrode body 700 and the terminal 200. Specifically, the current collector 500 integrally comprises a portion that is joined to the terminal 200 by crimping or the like, and a portion that is connected to the tab portion 730 of the electrode body 700 by welding or the like. The current collector 500 is made of a metal such as aluminum, aluminum alloy, copper, or copper alloy. The method of connecting the current collector 500 and the terminal 200 is not limited to crimping, and methods such as ultrasonic bonding, laser welding, resistance welding, or bolt and nut joining may be employed.

[0034] In this embodiment, the current collector 500 is a flat plate-shaped member parallel to the XY plane, but there are no particular limitations on the shape and size of the current collector 500. For example, the current collector 500 may have a connecting surface portion that forms a connecting surface parallel to the XZ plane. In this case, the connecting surface portion may be connected to a tab portion 730 that is extended in the Z-axis positive direction by ultrasonic bonding or the like.

[0035] [2. Configuration of the Electrode Body 700] Next, the configuration of the electrode body 700 according to this embodiment will be further explained with reference to Figures 3 to 7. Figure 3 is a perspective view showing the configuration of the electrode body 700 according to this embodiment. In Figure 3, the electrode plate 715 and the like wound in the electrode body 700 are partially unfolded and shown. Figure 4 is a schematic cross-sectional view showing the configuration of the laminate 701 according to this embodiment. Figure 5 is a schematic top view (viewed from the Z-axis positive direction) showing the configuration of the electrode body 700 according to this embodiment. In Figure 5, the approximate arrangement range of the tab portions 730A and 730B in the electrode body 700 is represented by a dotted rectangle. Figure 6 is a schematic top view showing the configuration of the tab portion 730 according to this embodiment. In Figure 6, the configuration of the electrode plate 715, which is the negative electrode plate 715A among the components of the wound laminate 701, is simply illustrated, and the separator 718 and the positive electrode plate 715B are not shown. In Figure 6, each of the multiple tabs 720 on the electrode plate 715 is represented by a patterned, elongated rectangle in the X-axis direction, in order to clearly show each of the multiple tabs 720. Figure 7 is a schematic diagram showing the positions of the multiple tabs 720 on the electrode plate 715 according to the embodiment.

[0036] As shown in Figure 3, the electrode body 700 according to this embodiment is formed by alternately stacking and winding a pair of electrode plates 715, namely a negative electrode plate 715A and a positive electrode plate 715B, via a separator 718. More specifically, as shown in Figure 4, a laminate 701 is formed by stacking a separator 718, a negative electrode plate 715A, another separator 718, and a positive electrode plate 715B in this order, and then winding the laminate. This forms an electrode body 700 comprising the wound negative electrode plate 715A and positive electrode plate 715B.

[0037] In Figure 3, the winding axis P, represented by the dashed line, is a virtual axis that serves as the central axis when winding the laminate 701. In this embodiment, the winding axis P is parallel to the Z-axis direction. The Z-axis direction is an example of a first direction. The electrode body 700 is formed in a flattened shape in a direction perpendicular to the winding axis P. In other words, the electrode body 700 is a wound and flattened electrode body. In this embodiment, the electrode body 700 has a flattened shape in the Y-axis direction, as shown in Figures 2, 3, and 5. The Y-axis direction is an example of a second direction. If the Z-axis direction is the first direction and the Y-axis direction is the second direction, the X-axis direction may be a third direction that intersects the first and second directions.

[0038] More specifically, the electrode body 700 comprises an electrode body main 710 that is flattened in the Y-axis direction and a tab portion 730 that protrudes from the electrode body main 710 in the Z-axis direction. As shown in Figure 5, the electrode body main 710 comprises a pair of curved portions 711 aligned in the X-axis direction and an intermediate portion 712 positioned between the pair of curved portions 711. That is, the laminate 701 including the negative electrode plate 715A and the positive electrode plate 715B has a relatively flat shape in the intermediate portion 712 and a curved shape in the curved portions 711.

[0039] As shown in Figure 4, the negative electrode plate 715A comprises a long, strip-shaped metal foil negative electrode current collector foil 716a and a negative electrode active material layer 717a formed on both sides of the negative electrode current collector foil 716a. The positive electrode plate 715B comprises a long, strip-shaped metal foil positive electrode current collector foil 716b and a positive electrode active material layer 717b formed on both sides of the positive electrode current collector foil 716b. In the electrode body 710, the negative electrode active material layer 717a of the negative electrode plate 715A and the positive electrode active material layer 717b of the positive electrode plate 715B are arranged opposite each other via a separator 718. The separator 718 is wound around the outermost circumference of the electrode body 710 at least once.

[0040] As the positive electrode current collector foil 716b and the negative electrode current collector foil 716a, any known material that is stable against oxidation-reduction reactions during charging and discharging can be used, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, and Al-Cd alloy. As the positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer, any known material that is capable of intercalating and releasing charge transport ions can be used.

[0041] The separator 718 is a microporous sheet made of resin. Any known material can be used as the material for the separator 718 used in the energy storage element 10, as long as it does not impair the performance of the energy storage element 10.

[0042] As shown in Figure 7, the electrode plate 715 according to this embodiment comprises a long, strip-shaped electrode plate body portion 716 and a plurality of tabs 720 protruding from the electrode plate body portion 716. In the negative electrode plate 715A, the electrode plate body portion 716 is the portion comprising the negative electrode current collector foil 716a and the negative electrode active material layer 717a (see Figure 4). In the negative electrode plate 715A, the tabs 720 (tabs 720a, see Figure 3) are the portions in which the negative electrode current collector foil 716a is exposed. In the positive electrode plate 715B, the electrode plate body portion 716 is the portion comprising the positive electrode current collector foil 716b and the positive electrode active material layer 717b (see Figure 4). In the positive electrode plate 715B, the tabs 720 (tabs 720b, see Figure 3) are the portions in which the positive electrode current collector foil 716b is exposed.

[0043] More specifically, the electrode plate body 716 has a plurality of tabs 720 that protrude from the sides of the electrode plate body 716 in the short direction (Z-axis direction). The plurality of tabs 720 are arranged in a line with predetermined intervals along the longitudinal direction of the electrode plate body 716.

[0044] In other words, when the negative electrode plate 715A, which has multiple tabs 720a, is wound, the tabs 720a are stacked in the Y-axis direction, thereby forming a tab portion 730A (see Figures 3 and 6). When the positive electrode plate 715B, which has multiple tabs 720b, is wound, the tabs 720b are stacked in the Y-axis direction, thereby forming a tab portion 730B (see Figure 3). As shown in Figures 2 and 3, the tab portions 730A and 730B are located on one side of the winding axis P at one end of the electrode body 710 in the Z-axis direction. In this embodiment, the tab portions 730A and 730B are located in the Y-axis negative direction at the Z-axis positive end of the electrode body 710. The tab portions 730A and 730B are spaced apart from each other in the X-axis direction.

[0045] In this wound electrode body 700, the electrode plate 715 is wound, stacking tabs 720 arranged in the longitudinal direction of the electrode plate 715, thereby forming a tab portion 730. Therefore, the tab pitch, which is the pitch between two adjacent tabs 720, is formed on the electrode plate 715 such that it increases as it moves away from the winding axis P, so that the positions of the winding direction (also called the direction in which the electrode plate 715 extends) of the multiple tabs 720 are aligned. For example, as shown in Figure 7, if the position of the edge of the tab 720 in the negative X-axis direction is defined as the position of the tab 720 in the X-axis direction, the tab pitch increases as it moves from the starting end 719 to the ending end 719e. The starting end 719 is the end of the electrode plate 715 where the winding begins, and is the end located on the innermost circumference of the electrode body 700 (see Figure 6). The ending end 719e is the end of the electrode plate 715 where the winding ends, and is the end located on the outermost circumference of the electrode body 700 (see Figure 6).

[0046] There are no particular limitations on how the position of tab 720 in the X-axis direction is defined. The position of tab 720 in the X-axis direction may be defined by the central position of tab 720 in the X-axis direction, or by the position of the edge of tab 720 in the positive X-axis direction.

[0047] The shape of the tab 720 does not have to be rectangular or substantially rectangular as shown in Figure 7. The shape of the tab 720 may be, for example, a trapezoid, where the width in the X-axis direction decreases as it moves away from the electrode plate body 716. In this case, the width in the X-axis direction of the edge in the Z-axis positive direction, which is the tip of the tab 720, that is, the length of the side corresponding to the top base of the trapezoid, may be defined as the width of the tab 720 in the X-axis direction. The position of the tab 720 in the X-axis direction may be defined by the central position of this width. For example, an R-shaped portion may be provided at least one of the ends (in other words, the root portion) in the X-axis direction of the tab 720 at the connection portion with the electrode plate body 716. For example, if an R-shaped portion is provided at the root portion in the X-axis negative direction of the tab 720, the position of the tab 720 in the X-axis direction may be defined by the position of the end in the X-axis negative direction of the R-shaped portion (i.e., the starting position of the R-shaped portion on the electrode plate body 716).

[0048] In this embodiment, the width W in the X-axis direction of the multiple tabs 720 is substantially the same. Specifically, the width W in the X-axis direction of the multiple tabs 720a included in the negative electrode tab portion 730A is substantially the same. The width W in the X-axis direction of the multiple tabs 720b included in the positive electrode tab portion 730B is substantially the same. The width in the X-axis direction of tab 720a and the width in the X-axis direction of tab 720b may or may not be the same.

[0049] In this embodiment, as shown in Figures 6 and 7, the electrode plate 715 has n tabs 720 (where n is an integer of 2 or more) that form one tab portion 730. In this case, as shown in Figure 7, the tab pitch, which is the pitch between two adjacent tabs 720, is T １ , T ２ , , T ｎ－１ If defined as such, these tab pitches are T １ <T ２ <...<T ｎ－１The following conditions are met. In the following, when distinguishing between multiple tabs 720, as shown in Figures 6 and 7, the first tab 72a is selected in order from the tab 720 closest to the starting end 719. １ , second tab 72a ２ , third tab 72a ３ ..., the n-1st tab 72a ｎ－１ , the nth tab 72a ｎ This is referred to as the second tab 72a. ２ and third tab 72a ３ The tab pitch between them is T ２ That is the case.

[0050] As described above, even if the condition is met that the tab pitch increases as it moves away from the starting end 719, the change in the pitch of two adjacent tabs (T ｎ -T ｎ－１ If the angle is constant, the positional misalignment of the tabs 720 may not be sufficiently corrected due to the inconsistent curvature of the electrode plate 715, etc. Therefore, in this embodiment, when determining the positions of the multiple tabs 720 on the electrode plate 715, additional conditions regarding the tab pitch are added to realize an electrode body 700 in which the positions of the multiple tabs 720 are aligned with greater precision. The characteristics of the tab pitch in the electrode body 700 according to this embodiment will be further explained below with reference to Figures 8A to 10, using comparative examples.

[0051] [3. Tab Pitch in Electrode Body 700] [3-1. Explanation of Comparative Example] First, as a comparative example, an example of a method for calculating the tab pitch in a conventional wound-type electrode body 1700 will be explained. Figure 8A is a schematic top view showing the configuration of the tab portion 1730 in the comparative example. In Figure 8A, only the configuration of one of the components of the electrode body 1700, the electrode plate 1715, is simply illustrated. Figure 8B is a diagram showing a model example for calculating the tab pitch. Figure 9A is a diagram schematically showing the first curved shape of the electrode plate 1715 in the comparative example. Figure 9B is a diagram schematically showing the second curved shape of the electrode plate 1715 in the comparative example. Figure 9C is a diagram schematically showing the third curved shape of the electrode plate 1715 in the comparative example. Figure 9A shows an example of the curved shape of the electrode plate 1715 in the inner circumference 1711a of the electrode body 1700, and Figure 9B shows an example of the curved shape of the electrode plate 1715 in the middle portion 1711b of the electrode body 1700. Figure 9C shows an example of the curved shape of the electrode plate 1715 in the outer circumference 1711c of the electrode body 1700.

[0052] The electrode body 1700 in the comparative example shown in Figure 8A is an example of a conventional wound-type electrode body, comprising a pair of curved portions 1711 and a main body intermediate portion 1712 positioned between the pair of curved portions 1711. In Figure 8A, only the curved portion 1711 in the X-axis positive direction of the pair of curved portions 1711 is shown. The electrode body 1700 comprises a wound electrode plate 1715, which consists of a portion included in the main body intermediate portion 1712 and a portion included in the curved portions 1711. The electrode plate 1715 has a plurality of tabs 1720, and in Figure 8A, eight of the plurality of tabs 1720 (tabs 79a to tabs 79h) are shown.

[0053] In the electrode body 1700 configured in this way, the tab pitch is determined such that it satisfies the condition that it becomes longer as it moves away from the starting end 1719 of the electrode plate 1715, and that the amount of change in the tab pitch of two adjacent tabs (the difference between the two tab pitches) is constant.

[0054] For example, as shown in FIG. 8B, assume a case where the distance between two tabs 1720 (tabs 1720A and 1720B) adjacent in the Y-axis direction after winding in the direction in which the electrode plate 1715 extends is defined as the tab pitch Ta. In this case, conventionally, the tab pitch Ta is considered to be the sum of the lengths of two straight portions and the lengths of two curved portions.

[0055] That is, Ta = La × 2 + Lb + Lc (see FIG. 8B). In this case, in the Y-axis direction, regardless of whether the positions of tabs 1720A and 1720B are close to the innermost circumference or the outermost circumference of the electrode body, or rather, regardless of where the positions of tabs 1720A and 1720B are in the stacking direction of the electrode plate 1715, the length La of the straight portion is considered to be constant. Furthermore, the shape of the curved portion of the electrode plate 1715 is considered to be a semi-arc shape. Therefore, the lengths Lb and Lc of the curved portions increase by a constant value obtained using the thickness of the laminate including the electrode plate 1715 as the position of the curved portion moves outward. The laminate is formed by laminating two electrode plates 1715 and two separators. Therefore, when the tab pitch adjacent to the tab pitch Ta in the direction in which the electrode plate 1715 extends is defined as Tb, the difference between Ta and Tb is considered to be constant.

[0056] That is, according to the conventional tab pitch calculation method, with the above constant difference being C, and the two adjacent tab pitches in the direction in which the electrode plate 1715 extends being T １ , T ２ , ···, T Ｍ , when assuming the tab pitch T Ｍ = T １ + (M - 1) × C. When a plurality of tab pitches are determined to satisfy such conditions, after winding the electrode plate 1715, a positional deviation as shown in FIG. 8A is likely to occur.

[0057] It is presumed that this misalignment of the tab 1720 is due to the fact that the shape of the curved portion of the electrode plate 1715 (corresponding to the lengths Lb and Lc in Figure 8B) differs depending on the position of the curved portion in the stacking direction of the electrode plate 1715. In other words, it is presumed that the misalignment of the tab 1720 occurs because the shape of the curved portion differs depending on whether the curved portion is located on the inner or outer circumference of the electrode body 1700.

[0058] For example, as shown in Figure 8A, consider a case where the curved portion 1711 of the electrode body 1700 is divided into an inner portion 1711a close to the inner circumference of the electrode body 1700, an outer portion 1711c close to the outer circumference of the electrode body 1700, and an intermediate portion 1711b between the inner portion 1711a and the outer portion 1711c. In this case, the shape of the curved portion of the electrode plate 1715 in the inner portion 1711a, the intermediate portion 1711b, and the outer portion 1711c changes as shown in Figures 9A to 9C. In Figures 9A to 9C, examples of the shape of the curved portion of the wound electrode plate 1715 are shown by thick solid lines, and the shape of the curved portion (semicircular arc shape) of the assumed electrode plate 1715V used in conventional tab pitch calculations is shown by a dashed line.

[0059] As shown in Figure 9A, in the inner circumference 1711a of the electrode body 1700, the electrode plate 1715 tends to have a roughly bent shape that passes inside the assumed electrode plate 1715V. In other words, it is presumed that this is due to the absence or scarcity of elements inside the curved portion of the electrode plate 1715 in the inner circumference 1711a. Therefore, the length of this curved portion becomes shorter than the length along the assumed electrode plate 1715V. As a result, the tab pitch obtained by conventional tab pitch calculations becomes longer than the actual tab pitch.

[0060] As shown in Figure 9B, in the intermediate portion 1711b of the electrode body 1700, the assumed semi-circular shape of the electrode plate 1715V and the curved portion of the actual electrode plate 1715 tend to be almost identical. This is presumed to be because the curved portion of the electrode plate 1715 in the intermediate portion 1711b is sandwiched between the inner circumference 1711a and the outer circumference 1711c. Therefore, the length of this curved portion is approximately the same as the length along the assumed electrode plate 1715V. As a result, the tab pitch obtained by conventional tab pitch calculations is approximately the same as the actual tab pitch.

[0061] As shown in Figure 9C, at the outer periphery 1711c of the electrode body 1700, the curved portion of the electrode plate 1715 tends to form so as to bulge outward from the assumed electrode plate 1715V. This is presumed to be due to the absence or scarcity of elements outside the curved portion of the electrode plate 1715 at the outer periphery 1711c. Therefore, the length of the curved portion becomes longer than the length along the assumed electrode plate 1715V. As a result, the tab pitch obtained by conventional tab pitch calculations becomes shorter than the actual tab pitch. Furthermore, at the outer periphery 1711c, the outward bulge of the electrode plate 1715 accumulates, and the further outward the curved portion is located, the greater the bulge of the electrode plate 1715 tends to be.

[0062] Simply put, the shape of the portion of the electrode plate 1715 included in the curved portion 1711 tends to be more pointed than a semicircular shape (see Figure 9A) the closer that portion is to the inner circumference of the electrode body 1700. The shape of the portion of the electrode plate 1715 included in the curved portion 1711 tends to be more bulging than a semicircular shape (see Figure 9C) the closer that portion is to the outer circumference.

[0063] As described above, due to the shape of the curved portion of the electrode plate 1715 varying depending on the position of the curved portion in the stacking direction of the electrode plate 1715, a displacement of the tab 1720 as shown in FIG. 8A may occur. For example, in the example shown in FIG. 8A, among the tabs 79b and 79c corresponding to the inner peripheral portion 1711a, the tab 79c outside the tab 79b is displaced in the +X-axis direction with respect to the tab 79b because the calculated tab pitch is longer than the actually necessary and sufficient tab pitch. For the tabs 79d and 79e corresponding to the intermediate portion 1711b, since the calculated tab pitch substantially coincides with the actually necessary tab pitch, the position of the tab 79e substantially coincides with the position of the tab 79d in the X-axis direction.

[0064] Regarding the tab 79f corresponding to the intermediate portion 1711b and the tab 79g corresponding to the outer peripheral portion 1711c, since the calculated tab pitch between the tab 79f and the tab 79g is shorter than the actually necessary tab pitch, the tab 79g is displaced in the -X-axis direction with respect to the tab 79f inside it. Among the tabs 79g and 79h corresponding to the outer peripheral portion 1711c, the tab 79h outside the tab 79g is displaced in the -X-axis direction with respect to the tab 79g because the calculated tab pitch is shorter than the actually necessary tab pitch.

[0065] [3 - 2. Conditions regarding the tab pitch according to the embodiment]In order to suppress the occurrence of displacement of the tab 720 due to the reasons as described above, in the power storage element 10 according to the present embodiment, the conditions regarding the tab pitch are changed according to the position of the tab corresponding to the tab pitch.

[0066] FIG. 10 is a diagram schematically showing the change in the tab pitch in the electrode body 700 according to the embodiment. In FIG. 10, illustration of a plurality of portions in the longitudinal direction of the electrode plate 715 is omitted, and a part of the plurality of tabs 720 provided on the electrode plate 715 (the first tab 72a １ to the third tab 72a ３ , the fifth tab 72a ５ to the seventh tab 72a ７ , the fifteenth tab 72a １５ to the seventeenth tab 72a １７ , the twenty-fifth tab 72a ２５ to the twenty-eighth tab 72a ２８) is illustrated.

[0067] In this embodiment, first, the first tab 72a １ , second tab 72a ２ , and the third tab 72a ３ The position of these three tabs 720 is determined so that their positions are aligned in the X-axis direction. For example, by prototyping the electrode plate 715 and / or theoretical calculations, the position of the first tab 72a １ , second tab 72a ２ , and the third tab 72a ３ The position is determined. The resulting first tab pitch T １ and the second tab pitch T ２ And then, T １ and T ２ We find Δ, which is the difference (also called the reference pitch difference) from T. ２ -T １ = Δ.

[0068] In this case, the nth tab pitch T ｎ is, T １ The value will depend on +(n-1)Δ. However, T ｎ = T １ When +(n-1)×Δ is used, as explained using Figures 9A to 9C, the shape of the curved portion of the electrode plate 715 changes depending on its position in the stacking direction of the electrode plate 715, and depending on its position, it may be difficult to determine an appropriate tab pitch. For example, at the outer circumference of the electrode body 700, T ｎ = T １ The tab pitch calculated using +(n-1)×Δ will be shorter than the actual tab pitch required.

[0069] Therefore, in this embodiment, the tab pitch on the outer periphery of the electrode body 700 is T １ The value should be greater than +(n-1) × Δ.

[0070] In other words, the energy storage element 10 according to this embodiment includes an electrode body 700 having a wound electrode plate 715. The electrode body 700 includes an electrode body main body 710 and a tab portion 730. The tab portion 730 is the end of the electrode body main body 710 and protrudes from the end in the Z-axis direction parallel to the winding axis of the electrode plate 715. The tab portion 730 includes n tabs 720 (n is an integer of 2 or more) which are part of the electrode plate 715 and are stacked in the Y-axis direction intersecting the Z-axis direction. The tab pitch, which is the pitch between two adjacent tabs 720 in the direction in which the electrode plate 715 extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let L be at least one integer satisfying n / 2 < L ≤ n-1, then T Ｌ >T １ It satisfies + (L-1) × Δ.

[0071] For example, if the electrode plate 715 has 30 tabs 720, then n = 30, and T １ <T ２ <, ... <T ２８ <T ２９ In this case, if L is at least one integer satisfying 15 < L ≤ 29, then T Ｌ >T １ The condition satisfies + (L-1) × Δ. In Figure 10, the 26th tab pitch T ２６ Regarding T ２６ >T １ It has been shown that the condition +25 × Δ is satisfied.

[0072] As described above, at the curved portions 711 at both ends of the wound electrode body 700, the outer electrode plate 715 tends to bulge outward more than the assumed semi-circular shape. As a result, the outer tabs 720, that is, the tabs 720 in the range close to the end of the winding of the electrode plate 715 (to the terminal portion 719e) in the direction in which the electrode plate 715 extends, tend to shift in the direction in which the electrode plate 715 extends, towards the beginning end of the winding (starting end portion 719). In relation to this problem, in the energy storage element 10 according to this embodiment, at least one tab pitch T on the outer circumference of the electrode body 700 Ｌ(n / 2 < L ≤ n-1) is defined as the reference pitch difference Δ and the tab pitch T. Ｌ The product of the number of tab pitches up to (L-1) and the first tab pitch T １ The value is made larger than the added value. This takes into account that the electrode plate 715 will bulge outwards, resulting in a relatively long tab pitch T. Ｌ This is achieved. As a result, the multiple tabs 720 stacked in the Y-axis direction (see Figure 6) become more easily aligned in the direction in which the electrode plate 715 extends (the X-axis direction in Figure 6). This allows for good bonding between the tab portion 730 and conductive members such as the current collector 500. Thus, the energy storage element 10 according to this embodiment is an energy storage element with improved reliability.

[0073] T Ｌ T １ There are no particular limitations on how large the value of +(L-1)×Δ should be. For example, T Ｌ = (T １ It can also be written as +(L-1)×Δ)×K (where K is a constant greater than 1), T Ｌ = (T １ It can also be expressed as +(L-1)×Δ)×K(L) (where K(L) is a function of L). Ｌ = (T １ It can also be written as +(L-1)×Δ) + K (where K is a constant greater than 0), T Ｌ = (T １ Alternatively, it could be expressed as +(L-1)×Δ) + K(L) (where K(L) is a function of L).

[0074] In the energy storage element 10 according to this embodiment, for all L that satisfy 2n / 3 < L ≤ n-1, T Ｌ >T １ It may also be stated that it satisfies + (L-1) × Δ. That is, if n = 30, all tab pitches from the 20th to the 29th (T ２０ , T ２１、 ..., T ２９ ) but, T Ｌ >T １ It may also satisfy +(L-1)×Δ.

[0075] According to this configuration, there are multiple tab pitches T near the end portion 719e of the electrode plate 715. ＬAll of these values ​​are relatively long, taking into account that the electrode plate 715 bulges outward at the curved portion 711. As a result, the positions of the multiple tabs 720 stacked in the Y-axis direction become even more aligned in the X-axis direction.

[0076] In the energy storage element 10 according to this embodiment, the three consecutive tab pitches are T Ｌ－２ , T Ｌ－１ , and, T Ｌ is, T Ｌ－１ -T Ｌ－２ <T Ｌ -T Ｌ－１ It may also be assumed that the following conditions are met. For example, if L = 27, then T ２６ -T ２５ <T ２７ -T ２６ The following conditions may be met. For example, the 25th tab pitch T ２５ The value is "100", and the 26th tab pitch T ２６ If it is "110", the 27th tab pitch T ２７ It could also be "125".

[0077] In this configuration, the tab pitches of at least three tabs that are close to and continuous with the end portion 719e of the electrode plate 715 are determined such that the difference in tab pitch increases as it approaches the end portion 719e of the electrode plate 715. As a result, these at least three tab pitches reflect the cumulative outward bulge of the electrode plate 715 at the outer circumference of the electrode body 700. Consequently, the positions of the multiple tabs 720 stacked in the Y-axis direction become more aligned in the X-axis direction.

[0078] The energy storage element 10 according to an embodiment of the present invention has a characteristic feature regarding the tab pitch in the range close to the starting end 719 of the electrode plate 715. Specifically, the energy storage element 10 according to an embodiment of the present invention can be described as follows, for example.

[0079] The energy storage element 10 according to this embodiment includes an electrode body 700 having a wound electrode plate 715. The electrode body 700 includes an electrode body main body 710 and a tab portion 730. The tab portion 730 is the end of the electrode body main body 710 and protrudes from the end of the electrode plate 715 in the Z-axis direction parallel to the winding axis P. The tab portion 730 includes n tabs 720 (n is an integer of 2 or more) which are part of the electrode plate 715 and are stacked in the Y-axis direction intersecting the Z-axis direction. The tab pitch, which is the pitch between two adjacent tabs 720 in the direction in which the electrode plate 715 extends, is T １ , T ２ , , T ｎ－１ Toshi, T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let S be at least one integer satisfying 3 ≤ S ≤ n / 2, then T Ｓ <T １ It satisfies + (S-1) × Δ.

[0080] For example, if n = 30, and L is at least one integer satisfying 3 ≤ S ≤ 15, then T Ｓ <T １ The condition satisfies + (S-1) × Δ. In Figure 10, the sixth tab pitch T ６ Regarding T ６ <T １ It has been shown that it satisfies +5 × Δ.

[0081] As described above, in the curved portions 711 at both ends of the wound electrode body 700, the inner circumference of the electrode plate 715 tends to have a substantially bent shape that passes inward from the assumed semi-circular shape. As a result, the inner circumference tabs 720, that is, the tabs 720 in the range close to the starting end (starting end 719) of the electrode plate 715 in the direction in which the electrode plate 715 extends, tend to shift away from the starting end 719 in the direction in which the electrode plate 715 extends. In relation to this problem, in the energy storage element 10 according to this embodiment, at least one tab pitch T included in the inner circumference of the electrode plate 715 Ｓ (3 ≤ L < n / 2) is defined as the reference pitch difference Δ and the tab pitch T. Ｌ The product of the number of tab pitches up to (L-1) and the first tab pitch T １The value is made smaller than the added value. This allows the electrode plate 715 to take on a substantially bent shape at the curved portion 711, resulting in a relatively short tab pitch T. Ｌ This is achieved. As a result, the multiple tabs 720 stacked in the Y-axis direction (see Figure 6) become more easily aligned in the direction in which the electrode plate 715 extends (the X-axis direction in Figure 6). This allows for good bonding between the tab portion 730 and conductive members such as the current collector 500. Thus, the energy storage element 10 according to this embodiment is an energy storage element with improved reliability.

[0082] T Ｓ T １ There are no particular limitations on how small the value of +(S-1)×Δ should be. For example, T Ｓ = (T １ It can also be written as +(S-1)×Δ)×R (where R is a constant less than 1), T Ｓ = (T １ It may also be expressed as +(S-1)×Δ)×R(S) (where R(S) is a function of S). Ｓ = (T １ It can also be written as +(S-1)×Δ)-R (where R is a constant greater than 0), T Ｓ = (T １ Alternatively, it may be written as +(S-1)×Δ)-R(S) (where R(S) is a function of the variable S).

[0083] In the energy storage element 10 according to this embodiment, for all S that satisfy 3 ≤ S ≤ n / 3, T Ｓ <T １ It may also be stated that the condition + (S-1) × Δ is satisfied. That is, if n = 30, then all tab pitches from the 3rd to the 10th (T ３ , T ４、 ..., T １０ ) but, T Ｓ <T １ It may also satisfy +(S-1)×Δ.

[0084] According to this configuration, there are multiple tab pitches T near the beginning of the winding of the electrode plate 715. Ｓ(S is all integers satisfying n / 3 < S ≤ n-1) is a relatively short value, taking into account that the electrode plate 715 has a roughly bent shape at the curved portion 711. As a result, the positions of the multiple tabs 720 stacked in the Y-axis direction become even more aligned in the X-axis direction.

[0085] In this embodiment, when the area between the outer and inner circumferences of the wound electrode body 700 is considered an intermediate portion, at least one tab pitch (the Qth tab pitch T) in the intermediate portion Ｑ ) is the difference between the reference pitch Δ and the tab pitch T Ｑ The product of the number of tab pitches up to (Q-1) and the first tab pitch T １ It may be considered approximately equal to the value obtained by adding [the specified value].

[0086] For example, if the electrode plate 715 has 30 tabs 720, then at least one tab pitch T of the 3rd to 10th tabs included in the inner circumference Ｓ However, T Ｓ <T １ The condition + (S-1) × Δ is satisfied, and the tab pitch T of the 20th to 29th tabs included in the outer periphery is also satisfied. Ｌ (T ２０ , T ２１、 ..., T ２９ At least one of the following is T Ｌ >T １ Let's assume the case where +(L-1)×Δ is satisfied. In this case, the tab pitch T of the 11th to the 19th tabs included in the intermediate section. Ｑ (T １１ , T １２、 ..., T １９ At least one of the following is T Ｑ ≒T １ It may also satisfy +(Q-1). In Figure 10, the 16th tab pitch T １６ Regarding T １６ ≒T １ It has been shown that it satisfies +15 × Δ. １６ ga T １ It is approximately equal to +15 × Δ, which means T １６ and T １ The difference with +15 × Δ is T １６ and T １ This means it is less than or equal to 0.2% of the larger of the two values ​​(+15 × Δ).

[0087] [4. Modified Examples] Figure 11 is a schematic plan view showing the configuration of a modified energy storage device 900 according to the embodiment. As shown in Figure 11, the energy storage element 10 according to the above embodiment may be used in the energy storage device 900. In this case, the technology of the present invention may be applied to at least one energy storage element 10 provided in the energy storage device 900.

[0088] The energy storage device 900 shown in Figure 11 comprises a plurality of energy storage units 800 arranged inside. Each energy storage unit 800 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may also include busbars (not shown) that electrically connect the plurality of energy storage elements 10, and busbars (not shown) that electrically connect the plurality of energy storage units 800. The energy storage unit 800 or the energy storage device 900 may also include a condition monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 900 may also consist of only one energy storage unit 800. In this case, the energy storage unit 800 may be referred to as the "energy storage device".

[0089] [5. Other Modifications] Although the energy storage element according to embodiments of the present invention and its modifications have been described above, the present invention is not limited to the embodiments and modifications. In other words, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is intended to include all modifications in the sense and scope equivalent to the claims.

[0090] The various features of the tab portion 730, tab 720, and tab pitch described in the embodiment may be present in at least one of the negative electrode tab portion 730A and the positive electrode tab portion 730B of the electrode body 700.

[0091] The electrode body 700 according to the embodiment has a plurality of tab pitches T Ｌ or T Ｓ Regarding this, it is sufficient to satisfy at least one of the following conditions 1 and 2.

[0092] Condition 1: Let L be at least one integer satisfying n / 2 < L ≤ n-1, then T Ｌ >T１ It satisfies + (L-1) × Δ.

[0093] Condition 2: Let S be at least one integer that satisfies 3 ≤ S ≤ n / 2, then T Ｓ <T １ It satisfies + (S-1) × Δ.

[0094] The electrode body 700 does not need to have both a positive electrode tab portion 730A and a negative electrode tab portion 730B on one side in the Z-axis direction (the positive Z-axis direction in this embodiment). The electrode body 700 may have a negative electrode tab portion 730A in the positive Z-axis direction and a positive electrode tab portion 730B in the negative Z-axis direction. The electrode body 700 may have a positive electrode tab portion 730B in the positive Z-axis direction and a negative electrode tab portion 730A in the negative Z-axis direction.

[0095] There are no particular limitations on the orientation of the electrode body 700 in the energy storage element 10. For example, the electrode body 700 may be housed in the container 100 in an orientation where the winding axis P is parallel to the X-axis direction. In this case, the electrode body 700 may have one tab portion 730 at each end of the electrode body body 710 in the X-axis direction. Furthermore, in this case, the current collector 500 may have a terminal connection portion connected to the shaft portion 201 of the terminal 200, and a leg portion extending from the terminal connection portion in the negative Z-axis direction and connected to the tab portion 730. That is, the electrode body 700 may be an electrode body wound horizontally so that the winding axis P is parallel to the Z-axis direction, or an electrode body wound vertically so that the winding axis P is parallel to the X-axis direction.

[0096] The energy storage element 10 may have only one of the pair of terminals 200. For example, consider the case where the tab portion 730B of the positive electrode of the electrode body 700 is electrically connected to the container 100, that is, when the container 100 is used as the positive electrode terminal. In this case, the energy storage element 10 may have only the terminal 200 of the pair of terminals 200 that is electrically connected to the tab portion 730A of the negative electrode.

[0097] The current collector 500 connected to the tab portion 730 of the electrode body 700 does not have to be directly connected to the terminal 200. For example, the current collector 500 may be connected to a conductive member directly connected to the terminal 200 by welding or crimping.

[0098] It is not essential that the terminal 200 has a shaft portion 201. For example, a shaft portion integrally provided with the current collector 500 may pass through the internal insulating member 400, the cover 120, the external insulating member 300, and the terminal 200, and be crimped on the outside of the terminal 200.

[0099] The supplementary information regarding the energy storage element 10 according to the above embodiment may also be applied to the energy storage element 10 provided in the energy storage device 900 according to the above modified example. Configurations constructed by arbitrarily combining the components included in the above embodiment and its modified examples are also included within the scope of the present invention.

[0100] This invention can be applied to energy storage elements such as lithium-ion secondary batteries.

[0101] 10 Energy storage element 100 Container 500 Current collector 700 Electrode body 701 Laminate 710 Electrode body main body 711 Curved section 712 Main body middle section 715 Electrode plate 715A Negative electrode plate 715B Positive electrode plate 716 Electrode plate main body section 716a Negative electrode current collector foil 716b Positive electrode current collector foil 717a Negative electrode active material layer 717b Positive electrode active material layer 718 Separator 719 Starting end section 719e End section 720, 720a, 720b Tab 730, 730A, 730B Tab section T Ｌ、 T Ｑ、 T Ｓ、 Ta 、 T ｎ Tab pitch

Claims

1. An electrode body including a wound electrode plate, the electrode body including an electrode body main body and a tab portion, the tab portion being an end portion of the electrode body main body and protruding from an end portion in a first direction parallel to the winding axis of the electrode plate, the tab portion including n (n is an integer of 2 or more) tabs that are a part of the electrode plate laminated in a second direction intersecting the first direction, and a tab pitch, which is a pitch between two adjacent tabs in the direction in which the electrode plate extends, being T p－１ , T ２ , ···, T ｎ－１ are defined as such, and T p－１ < T p (P is an integer of 2 or more and n or less), Δ = T ２ - T １ is defined as such, and when at least one integer L satisfying n / 2 < L ≤ n - 1 is defined as L, T Ｌ > T １ + (L - 1) × Δ is satisfied, the energy storage element.

2. For all L satisfying 2n / 3 < L ≤ n-1, T Ｌ >T １ A storage element according to claim 1, satisfying + (L-1) × Δ.

3. Furthermore, T Ｌ－１ -T Ｌ－２ <T Ｌ -T Ｌ－１ A storage element according to claim 1 or 2, which satisfies the following conditions.

4. The electrode body comprises a wound electrode plate, the electrode body comprising an electrode body body and a tab portion, the tab portion protruding from the end of the electrode body body in a first direction parallel to the winding axis of the electrode plate, the tab portion comprising n tabs (n is an integer of 2 or more) which are part of the electrode plate and are stacked in a second direction intersecting the first direction, and the tab pitch, which is the pitch between two adjacent tabs in the direction in which the electrode plate extends, is T １ , T ２ , , T ｎ－１ T p－１ <T p (P is an integer between 2 and n, and Δ = T ２ -T １ Let S be at least one integer satisfying 3 ≤ S ≤ n / 2, then T Ｓ <T １ A storage element that satisfies +(S-1)×Δ.

5. For all S satisfying 3 ≤ S ≤ n / 3, T Ｓ <T １ A storage element according to claim 4, satisfying + (S-1) × Δ.

Images