Method for manufacturing energy storage elements and windings

Abstract

This invention provides an energy storage element that improves the volumetric energy density of an energy storage system. [Solution] The energy storage element comprises a winding body 400 around which electrode plates are wound, a container 100 for housing the electrode body, and a pair of terminals 200 arranged outside the container in an electrically connected state to the winding body. The winding body comprises a winding body main body 410 and a pair of tab portions 420 protruding from the winding body main body. The winding body main body has a rectangular shape when viewed from the stacking direction of the electrode plates, and comprises a pair of chamfered cutouts 401 where a pair of adjacent corners of the rectangle are cut out, and the pair of tab portions protrude from the pair of chamfered cutouts.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power storage element and a wound body.

Background Art

[0002] Patent Document 1 discloses a secondary battery in which an electrode assembly having a chamfered portion is housed in a case.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in a power storage system using a secondary battery, it has been required to improve the volumetric energy density.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to improve the volumetric energy density as a power storage system.

Means for Solving the Problems

[0006] A power storage element according to one aspect of the present invention includes a wound body in which electrode plates are wound, a container that houses the wound body, and a pair of terminals that are electrically connected to the wound body and are disposed outside the container. The wound body includes a wound body main body and a pair of tab portions protruding from the wound body main body. The wound body main body has a shape based on a rectangle when viewed from the stacking direction of the electrode plates, and includes a pair of first cutout portions in which a pair of adjacent corners among the corners of the rectangle are chamfered and cut out. The pair of tab portions protrude from the pair of first cutout portions.

[0007] Another aspect of the present invention relates to a method for manufacturing a wound body in which strip-shaped electrode plates are wound, wherein the wound body comprises a wound body body and a pair of tab portions protruding from the wound body body, the wound body body is shaped based on a rectangle when viewed from the stacking direction of the electrode plates, and comprises a pair of chamfered notches where a pair of adjacent corners of the rectangle are cut out, the electrode plates comprises a plurality of recesses corresponding to the pair of chamfered notches and tab protrusions provided in the recesses, and the method for manufacturing the wound body comprises forming the pair of chamfered notches with the plurality of recesses and forming the pair of tab portions with the tab protrusions when winding the electrode plates. [Effects of the Invention]

[0008] According to the present invention, the volumetric energy density of the energy storage system can be improved. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the components arranged inside the container of the energy storage element according to the embodiment. [Figure 3] Figure 3 is a schematic diagram showing a portion of the positive electrode plate, negative electrode plate, and pair of separators in an electrode body according to an embodiment, in an unfolded state. [Figure 4] Figure 4 is a partial plan view of the positive electrode plate, negative electrode plate, and pair of separators provided in the electrode body according to the embodiment. [Figure 5] Figure 5 is an explanatory diagram showing the tab projection according to the embodiment. [Figure 6] Figure 6 is a cross-sectional view showing the current collector according to the embodiment in a state in which it is joined to a pair of tab portions of each electrode body. [Figure 7] Figure 7 is a cross-sectional view showing the connection structure between the electrode terminal and the current collector according to the embodiment. [Figure 8] Figure 8 is an explanatory diagram showing two electrode bodies according to the embodiment and an electrode body according to a comparative example. [Figure 9] Figure 9 is a schematic diagram showing an energy storage device equipped with an energy storage element according to an embodiment. [Modes for carrying out the invention]

[0010] (1) An energy storage element according to one aspect of the present invention comprises a winding body around which electrode plates are wound, a container housing the winding body, and a pair of terminals electrically connected to the winding body and located outside the container, wherein the winding body comprises a winding body body and a pair of tab portions protruding from the winding body body, the winding body body has a rectangular shape as viewed from the stacking direction of the electrode plates, and comprises a pair of chamfered notches where a pair of adjacent corners of the rectangle are cut out, and the pair of tab portions protrude from the pair of notches.

[0011] According to the energy storage element described in (1), the winding body has a pair of notches where a pair of corners are cut out in a chamfered manner. By bending these tabs, each tab can be housed in the space within the container formed by the notches. This reduces the space consumed by each tab within the container. This reduction allows for a larger space to be housed in the winding body within the container, making it possible to increase the volumetric energy density of the energy storage element. Therefore, the volumetric energy density of the energy storage system equipped with the energy storage element can be improved.

[0012] (2) In the energy storage element described in (1) above, the container may have a rectangular shape when viewed from the stacking direction, and may be provided with a pair of second notches in which a pair of corners of the rectangle corresponding to the first notch are cut out in a chamfered manner, and the terminals may be arranged in the second notches.

[0013] According to the energy storage element described in (2), since the terminals are arranged in the second notch of the container, a bus bar can be arranged in the space outside the container formed by the second notch to connect between the terminals. Therefore, the bus bar can be accommodated within the rectangle, and the consumption space outside the container due to the bus bar can be suppressed.

[0014] (3) In the energy storage element described in the above (1) or (2), it is also possible that two of the winding bodies are accommodated side by side in the stacking direction in the container.

[0015] According to the energy storage element described in (3), since two winding bodies are accommodated in the container, compared with the case of accommodating one large winding body, the dead space can be reduced, and the volume energy density can be further increased.

[0016] (4) In the energy storage element described in the above (3), a current collector for connecting the tab portion of the first winding body, which is one of the two winding bodies, the tab portion of the second winding body, which is the other, and the terminal is provided. The current collector includes a first connection portion connected to the tab portion of the first winding body, a second connection portion connected to the tab portion of the second winding body, and an intermediate portion between the first connection portion and the second connection portion, the intermediate portion protruding from the first connection portion and the second connection portion toward the terminal, and a shaft body protruding from the intermediate portion and caulked to the terminal.

[0017] According to the energy storage element described in (4), since the intermediate portion of the current collector protrudes from the first connection portion and the second connection portion toward the terminal, the shaft body can be brought closer to the terminal, and it becomes possible to easily caulk the shaft body to the terminal. Further, when the intermediate portion is flat with respect to the first connection portion and the second connection portion, it is necessary to lengthen each tab portion to connect to the first connection portion and the second connection portion. That is, the main body of the winding body becomes smaller due to the lengthening of each tab portion. In contrast, in this embodiment, since the intermediate portion protrudes from the first connection portion and the second connection portion toward the terminal, each tab portion does not need to be lengthened more than necessary, and thus the main body of the winding body can be enlarged, and the volume energy density can be improved.

[0018] (5) In the energy storage element according to (4) above, the head of the shaft body protruding from the terminal after caulking may be accommodated in a through-hole provided in a bus bar connected to the terminal.

[0019] According to the energy storage element described in (5), since the head of the shaft body is accommodated in the through-hole of the bus bar, the head of the shaft body is less likely to interfere when connecting the bus bar and the terminal, and the connection work can be easily performed.

[0020] (6) A method for manufacturing a wound body according to another aspect of the present invention is a method for manufacturing a wound body in which a strip-shaped electrode plate is wound. The wound body includes a wound body main body and a pair of tab portions protruding from the wound body main body. The wound body main body has a shape based on a rectangle when viewed from the stacking direction of the electrode plates, and includes a pair of first cutouts in which a pair of adjacent corners of the rectangle are chamfered. The electrode plate includes a plurality of recesses corresponding to the pair of first cutouts and tab protrusions provided in the recesses. The method for manufacturing the wound body forms the pair of first cutouts by the plurality of recesses and forms the pair of tab portions by the tab protrusions when winding the electrode plate.

[0021] According to the method for manufacturing a wound body described in (6), the wound body main body of the manufactured wound body has a pair of first cutouts in which a pair of corners are chamfered. By bending the tab portions, each tab portion can be accommodated in the space inside the container formed by the first cutouts. As a result, the consumption space of each tab portion inside the container can be reduced. By this reduction, the accommodation space for the wound body main body inside the container can be made larger, and the electric capacitance of the energy storage element can be increased. Therefore, the volumetric energy density as an energy storage system including the energy storage element can be improved.

[0022] (Embodiment) The following describes a method for manufacturing an energy storage element and a winding body according to an embodiment of the present invention, with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In addition, dimensions, etc., are not strictly illustrated in each figure. Furthermore, the same or similar components are denoted by the same reference numerals in each figure. The names of each component (each component) in this embodiment are those of this embodiment and may differ from the names of each component (each component) in the background art.

[0023] In the following description and drawings, the direction in which the pair of electrode terminals are aligned and the longitudinal direction of the container are defined as the X-axis direction, the thickness direction of the container and the thickness direction of the electrode body are defined as the Y-axis direction, and the direction in which the container body and lid are aligned and the electrode body and lid are 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 orientation of the energy storage element, the Z-axis direction may not be vertical, but for the sake of explanation, the Z-axis direction will be described as vertical.

[0024] 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. The same applies to the Y-axis and Z-axis directions. When simply referred to as "X-axis direction," it means either the bidirectional or unidirectional direction parallel to the X-axis. The same applies to the terminology related to the Y-axis and Z-axis.

[0025] Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the direction or orientation is not strictly accurate. For example, two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., include a difference of a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶6 Preferably, it is Ωm or higher, 1 × 10 7 Ωm or greater is more preferable, 1 × 10 10 A value of Ωm or higher is even more preferable.

[0026] [Energy storage element] A general description of the energy storage element 10 according to the embodiment will be given. 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 showing the components arranged inside the container 100 of the energy storage element 10 according to the embodiment.

[0027] 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 is used as a battery for propulsion or engine starting 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.

[0028] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery; it may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. Furthermore, the energy storage element 10 may be a battery using a solid electrolyte.

[0029] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of electrode terminals 200 (positive and negative), and a pair of external gaskets 500. As shown in Figure 2, the container 100 houses a pair of current collectors 300 (positive and negative), a pair of internal gaskets 600, and a pair of electrode bodies 400.

[0030] In addition to the above-mentioned components, the energy storage element 10 may also include a spacer positioned to the side of the electrode body 400, and an insulating film that encloses the electrode body 400, etc. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown in the illustration. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various types can be selected.

[0031] [Electrode body] The electrode body 400 is an energy storage element (power generation element) that can store electricity. The electrode body 400 is a wound body in which multiple electrode plates (positive electrode plate 430 and negative electrode plate 440) and multiple separators 450, 460 are stacked and wound together. The electrode body 400 comprises an electrode body main body 410 and a pair of tab portions 420 protruding from the electrode body main body 410. The electrode body main body 410 is an example of a wound body main body. The electrode body main body 410 has a rectangular shape when viewed from the Y-axis direction, and all corners of the rectangle are chamfered cutouts 401. In other words, the electrode body main body 410 has four cutouts 401, and each cutout 401 has a planar inclined surface that is inclined with respect to the XY plane. The electrode body 410 has an octagonal shape extending in the X-axis direction when viewed in the Y-axis direction, and an oval shape extending in the X-axis direction when viewed in the Z-axis direction. Therefore, the electrode body 410 has a flat portion 411 and a pair of curved portions 412 that sandwich the flat portion 411. The flat portion 411 is a flat area as a whole. Since the flat portion 411 is the main part of the electrode body 410, the stacking direction (Y-axis direction) of the positive electrode plate 430 and the negative electrode plate 440 in this flat portion 411 can also be said to be the overall stacking direction of the electrode body 400. Each curved portion 412 is curved so as to be convex outward when viewed in the Z-axis direction. Each curved portion 412 has a single cutout portion 401 formed therein.

[0032] The pair of tab portions 420 are groups of tabs that protrude from a pair of first cutout portions 401 in the Z-axis positive direction on the electrode body 410 in the X-axis positive and X-axis negative directions, with one tab portion 420 having the polarity of the positive electrode and the other tab portion 420 having the polarity of the negative electrode. Each tab portion 420 is shaped to fit within the reference rectangle of the electrode body 410.

[0033] Figure 3 is a schematic diagram showing a portion of the positive electrode plate 430, negative electrode plate 440, and pair of separators 450 and 460 provided in the electrode body 400 according to the embodiment, in an unfolded state. Figure 4 is a partial plan view of the positive electrode plate 430, negative electrode plate 440, and pair of separators 450 and 460 provided in the electrode body 400 according to the embodiment.

[0034] The positive electrode plate 430 is a strip-shaped electrode plate in which a positive electrode active material layer 432 is formed on at least one of the front and back surfaces of a current collector foil 431, which is a metal foil. The current collector foil 431 is made of aluminum or an aluminum alloy. The current collector foil 431 is formed in a strip shape, and a plurality of recesses 433 are formed at the location corresponding to the first cutout 401. Each recess 433 is formed in the shape of an isosceles triangle with a rounded vertex angle. In the recess 433 of the plurality of recesses 433, a tab projection 434 is formed in the recess 433 corresponding to one of the tab portions 420. The tab projection 434 protrudes inward from one of the equal sides of the recess 433. The tab projection 434 is shaped so as not to extend beyond the extension of the long side of the current collector foil 431. In other words, the tab projection 434 is shaped so as not to extend beyond the isosceles triangle formed by the recess 433. Therefore, the excess portion generated when cutting out the tab protrusion 434 during manufacturing can be reduced.

[0035] Figure 5 is an explanatory diagram showing a tab projection 434 according to an embodiment. In Figure 5, the tab projection 434 is shown with dot hatching, the isosceles triangle L1 which is the outer shape of the recess 433 is shown with a dashed line, and the circle L2 which serves as the reference for the curved portion 412 is shown with a dashed line. Figures 5(a), (b), and (c) show cases where the size of the curved portion 412 is different. In all cases, the straight line L3 extending from one equal side of the isosceles triangle L1 to the base angle opposite to that equal side, and the base of the isosceles triangle L1, form the outer shape of the tab projection 434. Here, if the straight line L3 is drawn from a point closer to the base than the point of contact between one equal side and the circle L2, it is possible to prevent the tab projection 434 from entering the curved portion 412. If the tab projection 434 enters the curved portion 412, the tab projection 434 will bend depending on the curved portion 412, which is undesirable. The side L4 at the tip of the tab projection 434 can be any shape as long as it is a straight line connecting the straight line L3 and the base of the isosceles triangle L1. However, if the tab projection 434 is too small, the resistance of the energy storage element 10 will increase, so it is preferable to design the tab projection 434 to be as large as possible. The same applies to the tab projection 444 of the negative electrode plate 440, which will be described later.

[0036] The positive electrode active material layer 432 includes a positive electrode active material, a binder, and a conductive material. As the positive electrode active material, any known material can be used as long as it is capable of intercalating and deintercalating charge transport ions. Preferably, as the positive electrode active material, a Ni-containing layered lithium transition metal oxide such as LiNiMO2 (where M is one or more metal elements selected from Mn, Co, Al, etc.) is used.

[0037] The positive electrode active material layer 432 is coated and laminated on at least one of the front and back surfaces of the current collector foil 431. The positive electrode active material layer 432 covers the entire surface of the current collector foil 431 in a generally continuous manner, with a predetermined gap between the edges of the current collector foil 431. Since the positive electrode active material layer 432 is not laminated on the tab protrusions 434, the tab protrusions 434 are entirely exposed from the positive electrode active material layer 432.

[0038] The negative electrode plate 440 is a strip-shaped electrode plate in which a negative electrode active material layer 442 is formed on at least one of the front and back surfaces of a current collector foil 441, which is a metal foil. Copper or a copper alloy is used for the current collector foil 441. The current collector foil 441 is formed in a strip shape, and a plurality of recesses 443 are formed at the location corresponding to the first cutout 401. Each recess 443 is formed in the shape of an isosceles triangle with a rounded vertex angle. Of the plurality of recesses 443, the recess 443 corresponding to the other tab portion 420 has a tab projection 444 that forms the tab portion 420. The tab projection 444 protrudes inward from one equal side of the recess 443. The tab projection 444 is shaped so as not to extend beyond the extension of the long side of the current collector foil 441. In other words, the tab projection 444 is shaped so as not to extend beyond the isosceles triangle formed by the recesses 443. Therefore, excess material generated when cutting out the tab protrusions 444 during manufacturing can be suppressed.

[0039] The negative electrode active material layer 442 contains a negative electrode active material, a binder, a thickener, etc. As the negative electrode active material, any known material can be used as long as it is a material capable of intercalating and deintercalating charge transport ions. Preferably, the negative electrode active material is a carbon material such as graphite, or a silicon compound such as silicon, silicon oxide, silicon-carbon composite, or a mixture thereof.

[0040] The negative electrode active material layer 442 is coated and laminated on at least one of the front and back surfaces of the current collector foil 441. The negative electrode active material layer 442 covers the entire surface of the current collector foil 441 at a predetermined distance from the edge of the current collector foil 441. Since the negative electrode active material layer 442 is not laminated on the tab protrusions 444, the tab protrusions 444 are exposed from the negative electrode active material layer 442.

[0041] The separators 450 and 460 are microporous sheets made of resin. Any known material can be used as the separator material, as long as it does not impair the performance of the energy storage element 10. As the separator, a woven fabric, nonwoven fabric, or a synthetic resin microporous membrane made of polyolefin resin such as polyethylene, which is insoluble in organic solvents, can be used. The separators 450 and 460 are formed in a strip shape, and a plurality of recesses 453 and 463 are formed at locations corresponding to the first missing portion 401. Each recess 453 and 463 is formed in the shape of an isosceles triangle with a rounded vertex angle.

[0042] As shown in Figure 3, the separator 450, positive electrode plate 430, separator 460, and negative electrode plate 440 are stacked in this order and wound around a virtual winding axis W parallel to the Z-axis direction to form the electrode body 400. Separators may be placed on the outermost periphery of the electrode body 400.

[0043] In other words, in the manufacturing method of the electrode body 400, when winding the electrode plates (positive electrode plate 430, negative electrode plate 440), a pair of first cutouts 401 can be formed by a plurality of recesses (recesses 433, 443), and a pair of tab portions 420 can be formed by tab protrusions (tab protrusions 434, 444).

[0044] [container] The container 100 houses a pair of current collectors 300, a pair of internal gaskets 600, and a pair of electrode bodies 400, and also holds a pair of electrode terminals 200 and a pair of external gaskets 500. The container 100 has a rectangular shape when viewed from the Y-axis direction, and all of the corners of the rectangle are second notches 101 that are cut out in a chamfered manner. In other words, each second notch 101 corresponds to each of the first notches 401 of the electrode body 400 and has the same shape. The container 100 is open in the Z-axis positive direction and comprises a container body 110, a lid 120 and a bottom 130 that close the opening of the container body 110.

[0045] The container body 110 is a cylindrical body with both ends open in the Z-axis direction. The container body 110 is rectangular in the Z-axis direction and octagonal in the Y-axis direction. Specifically, the container body 110 is formed in an annular shape with its axis direction being the Z-axis direction, and comprises a pair of first wall portions 113 facing each other in the Y-axis direction and a pair of second wall portions 114 facing each other in the X-axis direction. Each first wall portion 113 is a flat plate formed in an octagonal shape in plan view. Each second wall portion 114 is a flat plate formed in a rectangular shape in plan view.

[0046] The lid 120 is a plate with its longitudinal direction in the X-axis direction and closes the opening of the container body 110 in the Z-axis positive direction. Specifically, the middle portion 121 of the lid 120 in the X-axis direction is a flat plate portion parallel to the XY plane, and one end 122 and the other end 123 of the lid 120 in the X-axis direction are flat plate portions inclined toward the XZ plane toward the Z-axis negative direction as they move away from the middle portion 121. Through holes 124 are formed in one end 122 and the other end 123 of the lid 120. Although not shown in the figure, a liquid injection port is formed in the middle portion 121 of the lid 120. The liquid injection port is a part for injecting electrolyte into the container 100 during the manufacturing of the energy storage element 10, and is closed after injection.

[0047] The bottom body 130 is a plate with its longitudinal direction in the X-axis direction and closes the opening of the container body 110 in the Z-axis negative direction. Specifically, the middle portion 131 of the bottom body 130 in the X-axis direction is a flat plate portion parallel to the XY plane, and one end 132 and the other end 133 of the bottom body 130 in the X-axis direction are flat plate portions inclined toward the XZ plane toward the Z-axis positive direction as they move away from the middle portion 131. Gas discharge valves 134 are formed at one end 132 and the other end 133 of the bottom body 130 to release pressure when the pressure inside the container 100 rises. In other words, gas discharge valves 134 are provided in each of the pair of second notches 101 in the Z-axis negative direction among the four second notches 101. As a result, the gas flow path discharged from the gas discharge valves 134 can be contained within the rectangular standard of the container 100. This reduces the installation space required for the gas flow path. There may be only one gas discharge valve 134 provided for the bottom body 130.

[0048] After the electrode body 400 and the like are placed inside the container 100, the lid 120 and bottom 130 are joined to the container body 110 by welding or other means, thereby sealing the inside of the container 100. The material of the container body 110, lid 120 and bottom 130 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.

[0049] [Current collector] Each current collector 300 is a conductive member that is positioned between the electrode body 400 and the cover body 120 and individually connected to a pair of tab portions 420 of each electrode body 400. The current collector 300 can be made of aluminum, aluminum alloy, copper, or copper alloy, etc.

[0050] Figure 6 is a cross-sectional view showing the current collector 300 according to the embodiment joined to a pair of tab portions 420 of each electrode body 400. Here, one of the pair of electrode bodies 400 is referred to as the first electrode body 471, and the other as the second electrode body 472. The first electrode body 471 is an example of the first winding body, and the second electrode body 472 is an example of the second winding body.

[0051] As shown in Figure 6, the current collector 300 comprises a main body 301 and a shaft 302. The main body 301 is a plate-shaped member and integrally comprises a first connecting portion 310 and a second connecting portion 320, and an intermediate portion 330 between them. The intermediate portion 330 protrudes from the first connecting portion 310 and the second connecting portion 320 toward the electrode terminal 200.

[0052] The first connection portion 310 is one end of the current collector 300, and the tab portion 420 of the first electrode body 471 is connected to it by welding or the like. Specifically, the tab portion 420 of the first electrode body 471 is bent and connected so as to overlap the upper surface of the first connection portion 310. In this state, the first connection portion 310 is positioned along the inclined surface of the first cutout portion 401 of the first electrode body 471.

[0053] The second connection portion 320 is the other end of the current collector 300, and the tab portion 420 of the second electrode body 472 is connected to it by welding or the like. Specifically, the tab portion 420 of the second electrode body 472 is bent and connected so as to overlap the upper surface of the second connection portion 320. In this state, the second connection portion 320 is positioned along the inclined surface of the first cut portion 401 of the second electrode body 472.

[0054] The intermediate section 330 is provided with a through hole 331 into which the shaft 302 is inserted. The shaft 302 is crimped to the intermediate section 330 so as to protrude toward the electrode terminal 200. The intermediate section 330 faces the second notch 101 in the Z-axis positive direction of the container 100 and protrudes toward the second notch 101. The main body section 301 and the shaft 302 may be integrally formed.

[0055] [Internal gaskets and external gaskets] As shown in Figure 2, each internal gasket 600 is a plate-shaped, rectangular insulating sealing member positioned between the cover 120 and the current collector 300 to insulate and seal them. Specifically, the internal gasket 600 is positioned between one end 122 or the other end 123 of the cover 120 and the current collector 300. A through hole 604 is formed in the internal gasket 600.

[0056] Each external gasket 500 is a plate-shaped, rectangular insulating sealing member positioned between the cover 120 and the electrode terminals 200 to insulate and seal them. Specifically, the external gasket 500 is positioned between one end 122 or the other end 123 of the cover 120 and the electrode terminals 200. A through hole 504 is formed in the external gasket 500.

[0057] The outer gasket 500 and the inner gasket 600 are formed from electrically insulating resins such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof.

[0058] [Electrode terminal] The electrode terminals 200 are terminals electrically connected to each electrode body 400 via the current collector 300. In other words, the positive electrode terminal 200 is electrically connected to the positive electrode tab portion 420 of each electrode body 400 via the current collector 300, and the negative electrode terminal 200 is electrically connected to the negative electrode tab portion 420 of each electrode body 400 via the current collector 300. The electrode terminals 200 are flat and have a through hole 204 formed in their center.

[0059] Figure 7 is a cross-sectional view showing the connection structure between the electrode terminal 200 and the current collector 300 according to the embodiment. In Figure 7, an example is shown of the electrode terminal 200 located at one end 122 of the cover 120, but the same applies to the electrode terminal 200 located at the other end 123.

[0060] As shown in Figure 7, the shaft 302 of the current collector 300 passes through the through holes 604, 124, and 504 of the internal gasket 600, the cover 120, and the external gasket 500, respectively, and is then inserted into the through hole 204 of the electrode terminal 200 and crimped to the electrode terminal 200. As a result, the electrode terminal 200 is electrically connected to each electrode body 400 via the current collector 300 while positioned in the second notch 101 in the Z-axis positive direction in the container 100. The tip (head 303) of the shaft 302 protrudes from the electrode terminal 200 after crimping.

[0061] Here, multiple energy storage elements 10 arranged in the Y-axis direction are housed in a case 80. Adjacent energy storage elements 10 are electrically connected by plate-shaped busbars 85 extending in the Y-axis direction. The busbars 85 are joined by welding to the electrode terminals 200. Through holes 851 are formed in the busbars 85, and the head 303 of the shaft body 302 is housed within these through holes 851. Specifically, the entire head 303 is housed within the through holes 851. Conversely, when welding the busbars 85 to the electrode terminals 200, the head 303 acts as a positioning guide.

[0062] In Figure 7, the rectangle L10 that serves as the reference for the container 100 is shown by a dashed line. Since the electrode terminals 200 are located in the second notch 101 of the container 100, the busbar 85 can be housed within the rectangle L10. In other words, within the case 80, the busbar 85 can be placed in the space outside the container 100 formed by the second notch 101 and connected to the electrode terminals 200.

[0063] [Effects, etc.] As described above, according to this embodiment, the tab portions 420 protrude from the two Z-axis positive direction first cutouts 401. Therefore, each tab portion 420 can be accommodated in the space within the container 100 formed by the first cutouts 401 by bending it. This reduces the space consumed within the container 100 by each tab portion 420. This reduction allows for a larger accommodation space for the electrode body 410 within the container 100, making it possible to increase the volumetric energy density of the energy storage element 10. Therefore, the volumetric energy density of the energy storage system (such as the energy storage device 900 described later) equipped with the energy storage element 10 can be improved.

[0064] Since the electrode terminals 200 are located in the second notch 101 of the container 100, the busbar 85 can be placed in the space outside the container 100 formed by the second notch 101 and connected to the electrode terminals 200. Therefore, the busbar 85 can be contained within the standard rectangle of the container 100, and the space consumed outside the container 100 by the busbar 85 can be suppressed.

[0065] Since two wound electrode bodies 400 are housed inside the container 100, the electrical capacity can be increased. Figure 8 is an explanatory diagram showing two electrode bodies 400 according to the embodiment and an electrode body 400z according to a comparative example. Figure 8(a) is a partial cross-sectional view showing two electrode bodies 400 according to the embodiment and the container 100. Figure 8(b) is a partial cross-sectional view showing one electrode body 400z according to a comparative example and the container 100. Both containers 100 have the same housing space. Thus, when comparing the case in which two small electrode bodies 400 are housed in the same housing space (Figure 8(a)) with the case in which one large electrode body 400z is housed (Figure 8(b)), the curved portion 412 is smaller in Figure 8(a), so the excess space inside the container 100 is also smaller. As a result, the electrical capacity can be increased in Figure 8(a).

[0066] Since the intermediate portion 330 of the current collector 300 protrudes from the first connection portion 310 and the second connection portion 320 toward the electrode terminal 200, the shaft body 302 can be brought closer to the electrode terminal 200, and the shaft body 302 can be easily crimped to the electrode terminal 200. Here, if the intermediate portion is flat with respect to the first connection portion and the second connection portion, it would be necessary to lengthen each tab portion to connect to the first connection portion and the second connection portion. In other words, lengthening each tab portion would make the electrode body smaller. In contrast, in this embodiment, since the intermediate portion 330 protrudes from the first connection portion 310 and the second connection portion 320 toward the electrode terminal 200, it is not necessary to lengthen each tab portion 420, and thus the miniaturization of the electrode body 410 can be suppressed. Therefore, the volumetric energy density of the energy storage element 10 can be improved.

[0067] Since the head 303 of the shaft 302 is housed in the through hole 851 of the busbar 85, the head 303 of the shaft 302 functions as a positioning element for the busbar 85 when connecting the busbar 85 to the electrode terminal 200, making connection easier.

[0068] (others) The above describes a method for manufacturing an energy storage element according to embodiments of the present invention (including its modifications; the same applies hereinafter). However, the present invention is not limited to the above embodiments. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims. Configurations constructed by arbitrarily combining the components included in the above embodiments and their modifications are also included within the scope of the present invention.

[0069] In the above embodiment, a container 100 having a second notch 101 was illustrated, but the container does not necessarily have to have a second notch.

[0070] In the above embodiment, a case in which two electrode bodies 400 are housed in the container 100 was illustrated, but the container may house only one electrode body, or it may house three or more electrode bodies.

[0071] In the above embodiment, an electrode body 400 in which all four corners are first notches 401 was illustrated. However, an electrode body in which only a pair of adjacent corners are first notches may also be used. In this case, it is also possible to use a container in which only a pair of corners are second notches, and the electrode terminals can be placed in the pair of second notches.

[0072] The energy storage element 10 may be used in an energy storage device. In this case, the technology of the present invention only needs to be applied to at least one energy storage element 10 provided in the energy storage device. Figure 9 is a schematic diagram showing an energy storage device 900 equipped with an energy storage element 10 according to an embodiment. As shown in Figure 9, a plurality of energy storage units 910 are arranged inside the energy storage device 900. Each energy storage unit 910 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may include busbars (not shown) that electrically connect the plurality of energy storage elements 10, busbars (not shown) that electrically connect the plurality of energy storage units 910, etc. The energy storage unit 910 or the energy storage device 900 may include a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 900 may have only one energy storage unit 910. In other words, an energy storage unit 910 may be referred to as an energy storage device. [Industrial applicability]

[0073] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0074] 10 Energy storage elements 80 cases 85 Bus Bar 100 containers 101 Second notch 110 Container body 120 Lid 124, 204, 331, 504, 604, 851 through holes 130 Bottom body 134 Gas discharge valve 200 Electrode terminal (terminal) 300 Current collector 301 Main body 302 Shaft 303 Head 310 First connection section 320 Second connection section 330 Middle section 400, 400z electrode body (wound body) 401 First cutout 410 Electrode body (winding body) 411 Flat area 412 Curved section 420 Tab section 430 Positive electrode plate (electrode plate) 433, 443, 453, 463 recess 434, 444 Tab protrusions 440 Negative electrode plate (electrode plate) 450, 460 Separator 471 First electrode body (first coiled body) 472 Second electrode body (second coiled body)

Claims

1. A wound body around which electrode plates are wound, A container for housing the aforementioned wound body, The winding body is electrically connected to a pair of terminals located outside the container, The winding body comprises a winding body body and a pair of tab portions protruding from the winding body body. The winding body has a rectangular shape as viewed from the stacking direction of the electrode plates, and is provided with a pair of chamfered notches in which a pair of adjacent corners of the rectangle are cut out. The pair of tab portions protrude from the pair of first missing portions. Energy storage element.

2. The container has a rectangular shape when viewed from the stacking direction, and is provided with a pair of second notches in which a pair of corners of the rectangle corresponding to the first cutout are cut out in a chamfered manner. The terminal is located in the second notch. The energy storage element according to claim 1.

3. The container contains two of the wound bodies, arranged in the stacking direction. The energy storage element according to claim 2.

4. The device comprises a current collector that connects the tab portion of the first winding body, which is one of the two winding bodies, the tab portion of the second winding body, which is the other, and the terminal, The aforementioned current collector is The first connecting portion is connected to the tab portion of the first winding body, The second connecting portion is connected to the tab portion of the second winding body, An intermediate portion between the first connecting portion and the second connecting portion, the intermediate portion protruding from the first connecting portion and the second connecting portion toward the terminal, It comprises a shaft that protrudes from the intermediate portion and is crimped to the terminal, The energy storage element according to claim 3.

5. The head of the shaft body that protrudes from the terminal after crimping is housed in a through hole provided in the busbar connected to the terminal. The energy storage element according to claim 4.

6. A method for manufacturing a wound body in which strip-shaped electrode plates are wound, The winding body comprises a winding body body and a pair of tab portions protruding from the winding body body. The winding body has a rectangular shape as viewed from the stacking direction of the electrode plates, and is provided with a pair of chamfered notches in which a pair of adjacent corners of the rectangle are cut out. The electrode plate comprises a plurality of recesses corresponding to the pair of first cutouts, and tab protrusions provided in the recesses. The method for manufacturing the aforementioned wound body is as follows: When winding the electrode plate, the pair of first cutouts are formed by the plurality of recesses, and the pair of tab portions are formed by the tab protrusions. A method for manufacturing a wound body.

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