JP7793891B2 - Energy storage element - Google Patents

Description

The present invention relates to an energy storage element comprising an electrode body, a current collector, and an electrode terminal.

Conventionally, in energy storage elements comprising an electrode assembly, a current collector, and an electrode terminal, a configuration in which the current collector is connected to the lateral end of the electrode assembly and the electrode terminal is disposed above the electrode assembly is known. For example, Patent Document 1 discloses a secondary battery (energy storage element) in which current collector plates (current collectors) are connected to the left and right ends of an electrode group (electrode assembly), and external terminals (electrode terminals) are disposed above the electrode group.

International Publication No. 2017/056733

The electrode bodies included in conventional energy storage elements may vary in thickness. In such cases, it is preferable to arrange some kind of component to absorb the thickness variation of the electrode bodies, but this may result in the energy storage element becoming larger. For example, in the energy storage element disclosed in Patent Document 1 above, the thickness of the electrode bodies may vary. In particular, when multiple electrode bodies are arranged, the variation becomes greater. However, in the energy storage element disclosed in Patent Document 1 above, if some kind of component is arranged to absorb the thickness variation of the electrode bodies, the energy storage element becomes larger, and there is a risk that it will not be possible to reduce the size or increase the capacity of the energy storage element.

The present invention was made by the inventors by focusing on the above-mentioned problems, and aims to provide an energy storage element that can be made smaller and has a higher capacity.

To achieve the above object, one aspect of the present invention provides an energy storage element comprising a plurality of electrode bodies arranged in a first direction, a current collector connected to the ends of the plurality of electrode bodies in a second direction perpendicular to the first direction, electrode terminals arranged in a third direction perpendicular to the first and second directions and connected to the current collectors, and a spacer arranged between two of the plurality of electrode bodies, the spacer being positioned in the third direction such that both ends do not protrude beyond at least one of the plurality of electrode bodies.

According to this, in the energy storage element, a current collector is connected to the second-direction ends of multiple electrode bodies arranged in a first direction, electrode terminals are arranged in a third direction between the multiple electrode bodies, and a spacer is arranged between two electrode bodies, with both ends of the spacer in the third direction not protruding from at least one electrode body. In this way, when an energy storage element includes multiple electrode bodies arranged in a first direction, thickness variations in the first direction may occur. However, by disposing a spacer between the two electrode bodies, this thickness variation can be absorbed. Here, because current collectors are connected to the second-direction (e.g., left-right) ends of the electrode bodies, the current collectors prevent the spacers from protruding from the electrode bodies in the second direction. Alternatively, even if the spacers protrude from the electrode bodies in the second direction, as long as they do not protrude beyond the current collectors, the energy storage element will not become larger. In contrast, in the third direction (e.g., the up-down direction) where the electrode terminals are arranged, the spacers are likely to protrude from the electrode bodies. If the spacers protrude from all electrode bodies, the length (height) of the energy storage element in the third direction would increase, potentially resulting in an increased size of the energy storage element. For this reason, the spacer is positioned so that both ends do not protrude beyond at least one electrode body in the third direction. This prevents the energy storage element from becoming too large in the third direction, allowing for the energy storage element to be made smaller or have a higher capacity.

Furthermore, a sheet member may be provided that connects the ends of the two electrode bodies in the third direction.

In this energy storage element, by connecting the third direction ends of two electrode bodies that sandwich the spacer with a sheet member, the sheet member prevents the spacer from protruding from the third direction ends of the two electrode bodies. This makes it easy to achieve a configuration in which the spacer does not protrude from at least one electrode body in the third direction, thereby enabling the energy storage element to be made smaller or have a higher capacity. Alternatively, by configuring the spacer so that it does not protrude from the third direction ends of the two electrode bodies, contact between the spacer and the sheet member is prevented, thereby preventing the spacer from damaging the sheet member. By connecting the ends of the two electrode bodies with the sheet member, the spacer can be fixed in a sandwiched state between the two electrode bodies, making it easy to fix the spacer to multiple electrode bodies. This eliminates the need, for example, to bond the spacer to another member for fixation.

The sheet member may be arranged by being wrapped around the plurality of electrode bodies so as to surround the entire periphery of the plurality of electrode bodies.

By wrapping the sheet member so as to surround the entire periphery of the multiple electrode bodies, the sheet member prevents the spacers from protruding from both sides of the multiple electrode bodies in the third direction. This makes it easy to achieve a configuration in which both ends of the spacer do not protrude from at least one electrode body in the third direction, thereby enabling the energy storage element to be made smaller or have a higher capacity. By wrapping the sheet member so as to surround the entire periphery of the multiple electrode bodies, the spacers can be fixed in a sandwiched state between two electrode bodies, making it easy to fix the spacers to the multiple electrode bodies.

Each of the two electrode bodies has a pair of curved portions formed by winding an electrode plate and located at both ends in the third direction, and a flat portion connecting the pair of curved portions, and the spacer is disposed between the flat portions of the two electrode bodies and is disposed in a position such that both ends do not protrude beyond the pair of curved portions of at least one of the two electrode bodies in the third direction.

Flat, wound electrode bodies are prone to thickness variation, and when multiple flat, wound electrode bodies are arranged, the thickness variation may become greater. For this reason, a spacer is placed between the flat portions of two electrode bodies to absorb this thickness variation. Furthermore, by placing the spacer in a position in the third direction where both ends do not protrude beyond the pair of curved portions of at least one electrode body, the energy storage element can be prevented from becoming larger in the third direction, thereby enabling the energy storage element to be made smaller or have a higher capacity.

The spacer may be shorter than both of the two electrode bodies in the third direction.

By making the spacer shorter in the third direction than both of the two electrode bodies that sandwich it, it is possible to easily achieve a configuration in which both ends of the spacer do not protrude from the two electrode bodies. This prevents the energy storage element from becoming too large in the third direction, allowing for the energy storage element to be made smaller or have a higher capacity.

A plurality of the spacers may be arranged between the two electrode bodies.

By placing multiple spacers between the two electrode bodies, even if there is a large variation in the thickness of the multiple electrode bodies, the variation in thickness can be easily absorbed. This makes it possible to easily absorb the variation in the thickness of the multiple electrode bodies while also achieving a smaller size or higher capacity storage element.

The energy storage element of the present invention can be made smaller or have a higher capacity.

1 is a perspective view showing the appearance of an energy storage element according to an embodiment; 2 is a perspective view showing the internal configuration of a container of an energy storage element according to an embodiment, with a container body separated from the container. FIG. FIG. 2 is an exploded perspective view showing the components of the energy storage device according to the embodiment. FIG. 2 is a perspective view showing the configuration of an electrode body, a spacer, and a sheet member according to the embodiment. 3 is a cross-sectional view showing the configuration of an electrode body, a spacer, and a sheet member according to the embodiment. FIG. 10 is a cross-sectional view showing the configuration of an energy storage device including a plurality of spacers according to a modified example of the embodiment. FIG.

Hereinafter, with reference to the drawings, energy storage elements according to embodiments of the present invention (including variations thereof) will be described. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, 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. In each figure, dimensions and the like are not strictly depicted. In each figure, the same or similar components are designated by the same reference numerals.

In the following description and drawings, the X-axis direction is defined as the arrangement direction of a pair of electrode terminals (positive and negative, hereinafter) of the energy storage element, the arrangement direction of a pair of current collectors, the width direction of the electrode assembly, the extension direction of the winding axis of the electrode assembly, the direction in which the ends of the electrode assembly connected to the current collectors are arranged, or the direction in which the short sides of the container face each other. The Y-axis direction is defined as the arrangement direction of multiple electrode assemblies, the stacking direction of the electrode plates of the electrode assembly, the thickness direction of the electrode assembly, the arrangement direction of the electrode assembly and the spacer, the direction in which the long sides of the container face each other, or the thickness direction of the container. The Z-axis direction is defined as the height direction of the electrode assembly, the arrangement direction of the electrode terminals, current collectors, and electrode assembly, the arrangement direction of the container body and lid, or the up-down direction. The X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage mode, the Z-axis may not be the up-down direction; however, for convenience of explanation, the Z-axis will be described below as the up-down direction.

In the following description, for example, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Below, the Y-axis direction may also be referred to as the first direction, the X-axis direction as the second direction, and the Z-axis direction as the third direction. Expressions indicating relative directions or orientations, such as "parallel" and "orthogonal," also include cases where the directions or orientations are not strictly those of the same kind. For example, "two directions are orthogonal" does not only mean that the two directions are completely orthogonal, but also means that the directions are substantially orthogonal, i.e., there may be a difference of, for example, a few percent. Furthermore, in the following description, the term "insulation" refers to "electrical insulation."

(Embodiment)
[1 General Description of Energy Storage Element 10]
First, a general description of the energy storage element 10 according to the present embodiment will be given. Fig. 1 is a perspective view showing the appearance of the energy storage element 10 according to the present embodiment. Fig. 2 is a perspective view showing the internal configuration of the container 100 of the container 100 of the energy storage element 10 according to the present embodiment, with the container body 110 separated. Fig. 3 is an exploded perspective view showing each component of the energy storage element 10 according to the present embodiment. Specifically, Fig. 3 shows each component of the energy storage element 10, with the container body 110 not shown.

The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used for power storage or power supply applications. For example, the energy storage element 10 is used as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, boat, snowmobile, agricultural machinery, construction machinery, or electric railway vehicle. Examples of such automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and gasoline-powered automobiles. Examples of such electric railway vehicles include electric trains, monorails, linear motor cars, and hybrid electric trains equipped with both a diesel engine and an electric motor. The energy storage element 10 can also be used as a stationary battery for home or business use.

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 may be a capacitor. The energy storage element 10 may not be a secondary battery, but may be a primary battery that allows stored electricity to be used without the user having to charge it. The energy storage element 10 may be a battery that uses a solid electrolyte. The energy storage element 10 may also be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is illustrated as having a flat rectangular parallelepiped (square) shape, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a cylindrical shape, an elongated cylindrical shape, or a polygonal prism shape other than a rectangular parallelepiped, etc.

As shown in FIG. 1, the energy storage element 10 includes a container 100, a pair of electrode terminals 200 (positive and negative), and a pair of upper gaskets 300 (positive and negative). As shown in FIGS. 2 and 3, the container 100 contains a pair of lower gaskets 400 (positive and negative), a pair of current collectors 500 (positive and negative), multiple electrode bodies (two electrode bodies 600 and 700), a spacer 800, and a sheet member 900. An electrolyte (non-aqueous electrolyte) is enclosed within the container 100, but is not shown. There are no particular restrictions on the type of electrolyte, and various electrolytes can be selected as long as they do not impair the performance of the energy storage element 10. In addition to the above components, spacers or the like may be disposed to the sides or below the electrode bodies 600 and 700.

The container 100 is a rectangular parallelepiped (square or box-shaped) case comprising a container body 110 with an opening formed therein and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular, cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of flat, rectangular long side walls 111 on both sides (long sides) in the Y-axis direction, a pair of flat, rectangular short side walls 112 on both sides (short sides) in the X-axis direction, and a flat, rectangular bottom wall 113 on the negative Z-axis side. The lid 120 is a rectangular plate-shaped member that constitutes the lid of the container 100 and is arranged extending in the X-axis direction in the positive Z-axis direction of the container body 110. The lid 120 is equipped with a gas exhaust valve 121 that releases pressure inside the container 100 if the pressure rises excessively, and a liquid injection section (not shown) for injecting electrolyte into the container 100.

With this configuration, the container 100 is constructed so that the current collector 500, electrode bodies 600 and 700, spacer 800, etc. are housed inside the container body 110, and then the container body 110 and lid 120 are joined by welding or the like, thereby sealing the interior. The material of the container 100 (container body 110 and lid 120) is not particularly limited and can be a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used.

The electrode terminals 200 are terminal members (positive and negative electrode terminals) arranged in the positive Z-axis direction (above) of the current collector 500 and the electrode bodies 600 and 700, and are electrically connected to the electrode bodies 600 and 700 via the current collector 500. The electrode terminals 200 are metal members that conduct electricity stored in the electrode bodies 600 and 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 to store electricity in the electrode bodies 600 and 700. The electrode terminals 200 are formed from a conductive material such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 200 are connected (joined) to the current collector 500 by crimping or the like, and are attached to the lid body 120.

Specifically, the electrode terminal 200 has a shaft portion 201 (rivet portion) extending downward (in the negative Z-axis direction). The shaft portion 201 is inserted into and crimped into the through-hole 301 in the upper gasket 300, the through-hole 122 in the lid 120, the through-hole 401 in the lower gasket 400, and the through-hole 501 in the current collector 500. This fixes the electrode terminal 200, along with the upper gasket 300, the lower gasket 400, and the current collector 500, to the lid 120. In this way, the electrode terminal 200 is arranged in the Z-axis direction (a third direction perpendicular to the first and second directions) of the multiple electrode bodies (two electrode bodies 600 and 700) and is connected to the current collector 500. The method for connecting (joining) the electrode terminal 200 and the current collector 500 is not limited to crimping, and may involve welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping, such as screw fastening.

The multiple electrode bodies (two electrode bodies 600 and 700) each include a positive electrode plate, a negative electrode plate, and a separator, and are electricity storage elements (power generation elements) capable of storing electricity. The multiple electrode bodies (two electrode bodies 600 and 700) are arranged side by side in the Y-axis direction (first direction). The electrode bodies 600 and 700 are each formed by winding layers of positive and negative electrode plates with a separator sandwiched between them, forming a so-called vertically wound, flat, wound electrode body with an oval shape when viewed in the X-axis direction. The electrode bodies 600 and 700 have a similar configuration.

The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode substrate layer, which is a long strip of metal foil made of aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode substrate layer, which is a long strip of metal foil made of copper or a copper alloy. The positive electrode substrate layer and the negative electrode substrate layer can be made of any known material that is stable against oxidation-reduction reactions during charging and discharging, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymers, conductive glass, and Al-Cd alloys. 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 can be any known material that is capable of absorbing and releasing lithium ions. The separator can be made of any known material that does not impair the performance of the energy storage device 10.

Positive electrode active materials that can be used include polyanion compounds such as _LiMPO4 , _LiMSiO4 , and _LiMBO3 (M is one or more transition metal elements selected from Fe, Ni, _Mn , _{Co ,} etc.), lithium titanate, spinel-type lithium manganese oxides such as _LiMn2O4 and _{LiMn1.5Ni0.5O4} , and lithium transition metal oxides such as _LiMO2 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.). Examples of negative electrode active materials include lithium metal, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (e.g., Li ₄ Ti ₅ O ₁₂ ), polyphosphate compounds, and compounds of transition metals and Group 14 to Group 16 elements, such as Co ₃ O ₄ and Fe ₂ P, commonly referred to as conversion negative electrodes. The separator is a microporous sheet made of resin, and examples thereof include woven fabrics or nonwoven fabrics insoluble in organic solvents, and synthetic resin microporous membranes made of polyolefin resins such as polyethylene.

Specifically, the electrode assembly 600 is formed by winding a positive electrode plate and a negative electrode plate, with a separator interposed between them, so that they are offset from each other in the direction of the winding axis. The winding axis is an imaginary axis that serves as the central axis when winding the positive electrode plate, negative electrode plate, etc., and in this embodiment, it is a straight line that passes through the center of the electrode assembly 600 and is parallel to the X-axis direction. The positive electrode plate and negative electrode plate each have a portion (active material layer non-formed portion) at the end in the offset direction where no active material is formed (coated) and the substrate layer is exposed.

As a result, the electrode body 600 has a positive electrode side laminated portion 601 at one end in the winding axis direction, where the active material layer-free portions of the positive electrode plates are stacked and bundled, and a negative electrode side laminated portion 601 at the other end in the winding axis direction, where the active material layer-free portions of the negative electrode plates are stacked and bundled. The laminated portion 601 is a portion where the electrode plates (positive electrode plates or negative electrode plates) are stacked in the stacking direction (Y-axis direction). In other words, the electrode body 600 has an electrode body main portion 610 (see Figure 4) that forms the main body of the electrode body 600, and a pair of laminated portions 601 (positive electrode side and negative electrode side) that protrude from the electrode body main portion 610 on both sides in the X-axis direction. The electrode body main portion 610 is an oval-shaped portion (active material layer-forming portion) formed by winding the separator and the portions of the positive electrode plate and negative electrode plate on which the active material layers are formed (coated). Similarly, the electrode body 700 has an electrode body main body 710 (see FIG. 4) that forms the main body of the electrode body 700, and a pair of laminated sections 701 (positive and negative sides) that protrude from the electrode body main body 710 on both sides in the X-axis direction. A detailed description of the configuration of the electrode bodies 600 and 700 will be provided later.

The spacer 800 is a flat, rectangular member placed between the two electrode bodies 600 and 700 (see Figure 4). The spacer 800 is formed from an insulating resin, 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 a composite material thereof. The material of the spacer 800 is not particularly limited, and it may be formed from an insulating material such as a damping material or an elastic material such as rubber. If the insulation of the electrode bodies 600 and 700 is ensured or if insulation between the electrode bodies 600 and 700 is not necessary, the spacer 800 may be formed from a conductive material such as a metal material. A detailed description of the structure of the spacer 800 will be provided later.

The sheet member 900 is a sheet-like member (binding sheet) that connects the ends of the two electrode bodies 600 and 700 in the Z-axis direction (third direction). In this embodiment, the sheet member 900 connects both ends of the electrode bodies 600 and 700 in the Z-axis direction. Specifically, the sheet member 900 is an annular member that surrounds both sides of the electrode bodies 600 and 700 in the Y-axis direction and the Z-axis direction. The sheet member 900 can be formed, for example, from an insulating member such as any of the insulating resin materials that can be used for the spacer 800 described above. Note that if the insulation of the electrode bodies 600 and 700 is ensured by other members, or if insulation of the electrode bodies 600 and 700 is not necessary, the sheet member 900 may be formed from a conductive member such as a metal material. A detailed description of the configuration of the sheet member 900 will be provided later.

The current collectors 500 are disposed on both sides of the electrode bodies 600 and 700 in the X-axis direction and are current collecting members (positive and negative current collectors) that electrically connect the electrode bodies 600 and 700 to the electrode terminals 200. Specifically, the positive electrode side current collector 500 is connected (joined) to the positive electrode side laminated portions 601 and 701 of the electrode bodies 600 and 700 by welding or the like, and is also joined to the positive electrode side electrode terminal 200 by crimping or the like, as described above. The negative electrode side current collector 500 is connected (joined) to the negative electrode side laminated portions 601 and 701 of the electrode bodies 600 and 700 by welding or the like, and is also joined to the negative electrode side electrode terminal 200 by crimping or the like, as described above. In this way, the current collectors 500 are connected to the ends of the multiple electrode bodies (two electrode bodies 600 and 700) in the X-axis direction (a second direction perpendicular to the first direction).

The current collector 500 is a plate-like member that is bent and arranged along the side wall and lid 120, extending from the side wall of the container body 110 to the lid 120. The current collector 500 is fixedly connected (joined) to the lid 120. With this configuration, the electrode assemblies 600 and 700 are held (supported) in a suspended state from the lid 120 by the current collector 500, suppressing shaking due to vibration, impact, and the like. The material of the current collector 500 is not particularly limited, but for example, the positive electrode side current collector 500 is formed of a conductive material such as a metal, such as aluminum or an aluminum alloy, and the negative electrode side current collector 500 is formed of a conductive material such as a metal, such as copper or a copper alloy. Note that the current collector 500 and the laminated portions 601 and 701 may be connected (joined) by any welding method, such as ultrasonic welding, laser welding, or resistance welding, or by mechanical joining, such as crimping or screw fastening.

The positive and negative electrode collectors 500 are symmetrical with respect to the YZ plane. As shown in FIG. 3, each collector 500 has a terminal connection 510 and four electrode connection portions 520 extending from the terminal connection portion 510 in the negative Z-axis direction. The terminal connection portion 510 is the base of the collector 500 that is connected (joined) to the electrode terminal 200. The terminal connection portion 510 is a flat portion parallel to the XY plane in which the above-mentioned through hole 501 is formed, and is located on the electrode terminal 200 side (upper side, positive Z-axis direction) of the collector 500. The electrode connection portions 520 are the legs of the collector 500 that are connected (joined) to the electrode bodies 600 and 700. The electrode connection portion 520 is a long, flat portion that extends in the negative Z-axis direction from the X-axis end of the terminal connection portion 510 and is located on the electrode bodies 600 and 700 side (bottom side, negative Z-axis direction) of the current collector 500. In this embodiment, of the four electrode connection portions 520, two electrode connection portions 520 are located at positions that sandwich the laminated portion 601 of the electrode body 600 in the Y-axis direction and are joined to the laminated portion 601, and two electrode connection portions 520 are located at positions that sandwich the laminated portion 701 of the electrode body 700 in the Y-axis direction and are joined to the laminated portion 701.

The upper gasket 300 is a plate-shaped member (positive electrode upper gasket and negative electrode upper gasket) that is disposed between the lid 120 of the container 100 and the electrode terminal 200, providing insulation and sealing between the lid 120 and the electrode terminal 200. The lower gasket 400 is a plate-shaped member (positive electrode lower gasket and negative electrode lower gasket) that is disposed between the lid 120 and the current collector 500, providing insulation between the lid 120 and the current collector 500. The upper gasket 300 and the lower gasket 400 are formed, for example, from any insulating resin material that can be used for the spacer 800 described above.

[2. Description of the Configurations of the Electrode Bodies 600 and 700, the Spacer 800, and the Sheet Member 900]
Next, the configurations of the electrode bodies 600 and 700, the spacer 800, and the sheet member 900 will be described in detail. Fig. 4 is a perspective view showing the configurations of the electrode bodies 600 and 700, the spacer 800, and the sheet member 900 according to the present embodiment. Specifically, Fig. 4 is an exploded perspective view showing the respective components of the electrode bodies 600 and 700, the spacer 800, and the sheet member 900 shown in Fig. 3 . Fig. 5 is a cross-sectional view showing the configurations of the electrode bodies 600 and 700, the spacer 800, and the sheet member 900 according to the present embodiment. Specifically, Fig. 5 is a cross-sectional view showing the configuration when the central portion of the energy storage element 10 shown in Fig. 1 is cut along a plane parallel to the YZ plane.

As described above, the electrode bodies 600 and 700 are each flat, wound electrode bodies with an oval shape when viewed in the X-axis direction, in which a separator is sandwiched between a positive electrode plate and a negative electrode plate and wound around the electrode body. In other words, the electrode body main body portions 610 and 710 are elongated columnar or cylindrical portions formed by winding the separator and the portions of the positive and negative electrode plates on which the active material layers are formed. As a result, as shown in FIGS. 4 and 5 , the electrode body main body portion 610 has a pair of electrode body flat portions 611 and 612 located on both sides in the Y-axis direction (first direction) and a pair of electrode body curved portions 613 and 614 located at both ends in the Z-axis direction (third direction). The electrode body main body portion 710 has a pair of electrode body flat portions 711 and 712 located on both sides in the Y-axis direction (first direction) and a pair of electrode body curved portions 713 and 714 located at both ends in the Z-axis direction (third direction).

The electrode flat portion 611 is a flat, rectangular portion extending parallel to the XZ plane oriented in the negative Y-axis direction, connecting the pair of electrode curved portions 613 and 614, and is disposed opposite the long side wall portion 111 of the container body 110 in the negative Y-axis direction. The electrode flat portion 612 is a flat, rectangular portion extending parallel to the XZ plane oriented in the positive Y-axis direction, connecting the pair of electrode curved portions 613 and 614, and is disposed opposite the spacer 800. The electrode curved portion 613 is a curved portion that curves in a semicircular arc shape so as to protrude in the positive Z-axis direction when viewed from the X-axis direction, and extends in the X-axis direction, and is disposed opposite the lid 120. The electrode curved portion 614 is a curved portion that curves in a semicircular arc shape so as to protrude in the negative Z-axis direction when viewed from the X-axis direction, and extends in the X-axis direction, and is disposed opposite the bottom wall portion 113 of the container body 110.

The electrode body flat portion 711 is a flat, rectangular portion extending parallel to the XZ plane oriented in the negative Y-axis direction, connecting the pair of electrode body curved portions 713 and 714, and is arranged opposite the spacer 800. The electrode body flat portion 712 is a flat, rectangular portion extending parallel to the XZ plane oriented in the positive Y-axis direction, connecting the pair of electrode body curved portions 713 and 714, and is arranged opposite the long side wall portion 111 of the container body 110 in the positive Y-axis direction. The electrode body curved portion 713 is a curved portion that curves in a semicircular arc shape so as to protrude in the positive Z-axis direction when viewed from the X-axis direction, and extends in the X-axis direction, and is arranged opposite the lid 120. The electrode body curved portion 714 is a curved portion that curves in a semicircular arc shape so as to protrude in the negative Z-axis direction when viewed from the X-axis direction, and extends in the X-axis direction, and is arranged opposite the bottom wall portion 113 of the container body 110.

As described above, the sheet member 900 is a member that connects the ends (curved portions) of the two electrode bodies 600 and 700 in the Z-axis direction (third direction). That is, the sheet member 900 connects the electrode body curved portions 613 and 713 of the electrode body main bodies 610 and 710, and also connects the electrode body curved portions 614 and 714. Specifically, the sheet member 900 has a pair of opposing first sheet portions 910 and 920 on both side surfaces in the Y-axis direction, and a pair of opposing second sheet portions 930 and 940 on both upper and lower surfaces in the Z-axis direction. The Z-axis end portions of the pair of first sheet portions 910 and 920 are connected to the Y-axis end portions of the pair of second sheet portions 930 and 940, forming the rectangular, annular sheet member 900. As a result, the sheet member 900 is wrapped around the multiple electrode bodies (two electrode bodies 600 and 700) so as to surround the entire periphery of the multiple electrode bodies (two electrode bodies 600 and 700).

The sheet member 900 may have a rectangular annular shape before being wrapped around the electrode bodies 600 and 700 (before being constrained), or may have a curved shape such as a circular annular shape before being wrapped around the electrode bodies 600 and 700 (before being constrained). In other words, the sheet member 900 may have a curved shape before being wrapped around the electrode bodies 600 and 700 (before being constrained), and after being wrapped around the electrode bodies 600 and 700 (after being constrained), it may be in close contact with the electrode bodies 600 and 700, thereby forming a pair of planar first sheet portions 910 and 920 and a pair of planar second sheet portions 930 and 940. Furthermore, the sheet member 900 may be a single sheet (or multiple sheets) before being wrapped around the electrode bodies 600 and 700, and after being wrapped around the electrode bodies 600 and 700, the ends of the sheets may be connected (joined) to constrain the electrode bodies 600 and 700.

The first sheet portions 910 and 920 are rectangular sheet-like portions parallel to the XZ plane, and are positioned to sandwich the electrode bodies 600 and 700 and the spacer 800 in the Y-axis direction. The first sheet portions 910 and 920 are adjacent to the second sheet portions 930 and 940, and have a larger outer surface area than the second sheet portions 930 and 940. The first sheet portion 910 is positioned in the negative Y-axis direction of the electrode body flat portion 611 of the electrode body main body portion 610, and is positioned between the electrode body flat portion 611 and the long side wall portion 111 of the container body 110 in the negative Y-axis direction, abutting the electrode body flat portion 611 and the long side wall portion 111. The first sheet portion 920 is positioned in the positive Y-axis direction of the electrode flat portion 712 of the electrode body main body portion 710, and is positioned between the electrode flat portion 712 and the long side wall portion 111 of the container body 110 in the positive Y-axis direction, in contact with the electrode flat portion 712 and the long side wall portion 111.

The second sheet portions 930 and 940 are rectangular sheet-like portions parallel to the XY plane and are arranged across the two electrode bodies 600 and 700, sandwiching the electrode bodies 600 and 700 and the spacer 800 in the Z-axis direction. The second sheet portions 930 and 940 are adjacent to the first sheet portions 910 and 920 and have a smaller outer surface area than the first sheet portions 910 and 920. Note that the first sheet portions 910 and 920 may have a smaller outer surface area than the second sheet portions 930 and 940. The second sheet portion 930 is arranged in the positive Z-axis direction of the electrode body curved portions 613 and 713 of the electrode body main body portions 610 and 710, and is arranged abutting the electrode body curved portions 613 and 713 between the electrode body curved portions 613 and 713 and the cover body 120. The second sheet portion 940 is positioned in the negative Z-axis direction of the electrode curved portions 614 and 714 of the electrode body main portions 610 and 710, and is positioned between the electrode curved portions 614 and 714 and the bottom wall portion 113 of the container body 110, abutting against the electrode curved portions 614 and 714 and the bottom wall portion 113.

In this embodiment, the sheet member 900 (first sheet portions 910 and 920 and second sheet portions 930 and 940) is formed of a heat-shrinkable sheet-like material or adhesive tape. The sheet member 900 is, for example, a ring-shaped shrink sheet made of a heat-shrinkable resin or the like, and is configured to be wrapped around the electrode bodies 600 and 700 and then shrink by heat to constrain the electrode bodies 600 and 700. The sheet member 900 may be an adhesive tape (insulating tape) such as glass cloth tape, and may be configured to constrain the electrode bodies 600 and 700 by connecting both ends of the electrode bodies 600 and 700 in the Z-axis direction. In this case, the sheet member 900 may include two sheet members: one sheet member connecting the ends of the electrode bodies 600 and 700 in the positive Z-axis direction, and the other sheet member connecting the ends of the electrode bodies 600 and 700 in the negative Z-axis direction. In other words, the first sheet portions 910 and 920 may be divided in the Z-axis direction.

As shown in FIG. 5 , the spacer 800 is disposed between the flat portions of the two electrode bodies 600 and 700. Specifically, the spacer 800 is disposed between the electrode body flat portions 612 and 711 of the electrode body main portions 610 and 710 of the electrode bodies 600 and 700, and abuts against the electrode body flat portions 612 and 711. The spacer 800 is disposed in a position in the Z-axis direction (third direction) such that both ends do not protrude from at least one of the multiple electrode bodies (electrode bodies 600 and 700). In other words, the spacer 800 is disposed in a position in the Z-axis direction (third direction) such that both ends do not protrude from a pair of curved portions (electrode body curved portions 613 and 614, or electrode body curved portions 713 and 714) of at least one of the two electrode bodies 600 and 700.

In this embodiment, the spacer 800 is shorter than both of the two electrode bodies 600 and 700 in the Z-axis direction (third direction). As a result, the spacer 800 is positioned in a position in the Z-axis direction such that both ends of the spacer 800 do not protrude from either of the two electrode bodies 600 and 700. In other words, the spacer 800 is positioned in a position in the Z-axis direction such that it does not protrude from the electrode body curved portions 613 and 614 and the electrode body curved portions 713 and 714, which are pairs of curved portions of both of the two electrode bodies 600 and 700. Specifically, the spacer 800 is positioned in a position in the Z-axis direction such that it protrudes from the electrode body flat portions 612 and 711 of the electrode body main portions 610 and 710 of the electrode bodies 600 and 700, but does not protrude from the electrode body curved portions 613 and 614 and the electrode body curved portions 713 and 714. In this embodiment, the electrode body curved portions 613 and 614 and the electrode body curved portions 713 and 714 of the electrode bodies 600 and 700 are arranged so as to protrude from the spacer 800. As a result, the spacer 800 does not abut against the second sheet portions 930 and 940 of the sheet member 900.

[3. Explanation of Effects]
As described above, in the energy storage device 10 according to the embodiment of the present invention, the current collector 500 is connected to the ends in the second direction (X-axis direction) of the two electrode bodies 600 and 700 aligned in the first direction (Y-axis direction), and the electrode terminal 200 is arranged in the third direction (Z-axis direction) of the electrode bodies 600 and 700. A spacer 800 is arranged between the two electrode bodies 600 and 700, and both ends of the spacer 800 in the third direction do not protrude from at least one of the electrode bodies (in this embodiment, both of the electrode bodies 600 and 700). In this way, when the energy storage device 10 includes two electrode bodies 600 and 700 aligned in the first direction, there may be variations in thickness in the first direction. However, by arranging the spacer 800 between the two electrode bodies 600 and 700, this variation in thickness can be absorbed. Here, because the current collector 500 is connected to the ends of the electrode bodies 600 and 700 in the second direction (left-right direction), the current collector 500 prevents the spacer 800 from protruding from the electrode bodies 600 and 700 in the second direction. Alternatively, even if the spacer 800 protrudes from the electrode bodies 600 and 700 in the second direction, the energy storage device 10 will not become larger as long as it does not protrude further than the current collector 500. In contrast, in the third direction (up-down direction), the spacer 800 is likely to protrude from the electrode bodies 600 and 700. If the spacer 800 protrudes from the electrode bodies 600 and 700, the length (height) of the energy storage device 10 in the third direction will increase, potentially resulting in an increase in the size of the energy storage device 10. Therefore, the spacer 800 is positioned in a position in the third direction such that both ends do not protrude from at least one electrode body (in this embodiment, both electrode bodies 600 and 700). This prevents the energy storage device 10 from becoming larger in the third direction, thereby enabling the energy storage device 10 to be made smaller or have a higher capacity.

By connecting the third-direction ends of the two electrode bodies 600 and 700 sandwiching the spacer 800 with the sheet member 900, the sheet member 900 prevents the spacer 800 from protruding from the third-direction ends of the two electrode bodies 600 and 700. This makes it easy to achieve a configuration in which the spacer 800 does not protrude from at least one electrode body (in this embodiment, both electrode bodies 600 and 700) in the third direction, thereby enabling the energy storage device 10 to be made smaller or have a higher capacity. Alternatively, by configuring the spacer 800 so that it does not protrude from the third-direction ends of the two electrode bodies 600 and 700, contact between the spacer 800 and the sheet member 900 is prevented, thereby preventing the spacer 800 from damaging the sheet member 900. Because the sheet member 900 connects the ends of the two electrode bodies 600 and 700, the spacer 800 can be fixed in a sandwiched state between the two electrode bodies 600 and 700, making it easy to fix the spacer 800 to the two electrode bodies 600 and 700. This eliminates the need to, for example, bond and fix the spacer 800 to another member.

By wrapping the sheet member 900 so as to surround the entire periphery of the two electrode bodies 600 and 700, the sheet member 900 prevents the spacer 800 from protruding from both sides of the two electrode bodies 600 and 700 in the third direction. This makes it easy to achieve a configuration in which both ends of the spacer 800 do not protrude from at least one electrode body (in this embodiment, both electrode bodies 600 and 700) in the third direction, thereby enabling the energy storage element 10 to be made smaller or have a higher capacity. By wrapping the sheet member 900 so as to surround the entire periphery of the two electrode bodies 600 and 700, the spacer 800 can be fixed in a sandwiched state between the two electrode bodies 600 and 700, making it easy to fix the spacer 800 to the two electrode bodies 600 and 700.

Flat, wound electrode bodies are prone to thickness variation, and when two flat, wound electrode bodies 600 and 700 are arranged, there is a risk of the thickness variation becoming greater. Therefore, a spacer 800 is arranged between the electrode body flat portions 612 and 711 of the two electrode bodies 600 and 700 to absorb this thickness variation. Furthermore, the spacer 800 is arranged in a position in the third direction such that both ends do not protrude beyond a pair of curved portions of at least one electrode body (in this embodiment, the electrode body curved portions 613 and 614, and the electrode body curved portions 713 and 714). This prevents the energy storage element 10 from becoming larger in the third direction, thereby enabling the energy storage element 10 to be made smaller or have a higher capacity.

By making the spacer 800 shorter in the third direction than both of the two electrode bodies 600 and 700 that sandwich the spacer 800, it is possible to easily achieve a configuration in which both ends of the spacer 800 do not protrude from the two electrode bodies 600 and 700. This prevents the energy storage element 10 from becoming larger in the third direction, thereby enabling the energy storage element 10 to be made smaller or have a higher capacity. By making the spacer 800 shorter in the third direction than both of the two electrode bodies 600 and 700, it is possible to prevent the spacer 800 from contacting and damaging the sheet member 900 that connects the two electrode bodies 600 and 700.

[4. Description of Modifications]
Although the energy storage device 10 according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. The embodiment disclosed herein is an example in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

For example, in the above embodiment, one spacer 800 is disposed between the two electrode bodies 600 and 700. However, multiple spacers 800 may be disposed between the two electrode bodies 600 and 700. Figure 6 is a cross-sectional view showing the configuration of a storage element 11 including multiple spacers 800 according to a modified example of this embodiment. Specifically, Figure 6 corresponds to Figure 5. As shown in Figure 6, the storage element 11 includes two spacers 800 disposed between the electrode bodies 600 and 700, stacked in the Y-axis direction. Specifically, the two spacers 800 are disposed between the flat portions 612 and 711 of the electrode bodies 600 and 700. Note that the number of spacers 800 is not particularly limited, and three or more spacers 800 may be disposed between the electrode bodies 600 and 700. The remaining configuration of this modified example is the same as that of the above embodiment. As described above, the storage element 11 according to this modified example can achieve the same effects as those of the above embodiment. In particular, in this modified example, by placing multiple spacers 800 between the two electrode bodies 600 and 700, even if there is a large variation in the thickness of the electrode bodies 600 and 700, this variation in thickness can be easily accommodated. This makes it possible to easily accommodate the variation in the thickness of the electrode bodies 600 and 700 while also achieving a smaller size or higher capacity for the energy storage element 11.

In the above embodiment, the spacer 800 is not in contact with the second sheet portions 930 and 940 of the sheet member 900. However, the spacer 800 may be in contact with at least one of the second sheet portions 930 and 940. In other words, the spacer 800 may have the same length in the Z-axis direction as the electrode bodies 600 and 700.

In the above embodiment, the electrode bodies 600 and 700 have an oval shape when viewed in the Z-axis direction, but they may also have a circular, elliptical, or polygonal shape, and the shape is not particularly limited. The shape of the electrode bodies 600 and 700 is not limited to a wound type, but may also be a stack type in which flat electrode plates are layered, or a shape in which the electrode plates are folded like an accordion. The electrode bodies 600 and 700 may have tabs.

In the above embodiment, two electrode bodies, electrode bodies 600 and 700, are arranged side by side in the Y-axis direction, but three or more electrode bodies may be arranged side by side in the Y-axis direction. In this case, it is sufficient that at least one spacer 800 is arranged between at least two electrode bodies. In other words, spacers 800 may be arranged between all electrode bodies, or spacers 800 may be arranged between any two electrode bodies.

In the above embodiment, the electrode bodies 600 and 700 have the same length in the Z-axis direction, but they may have different lengths in the Z-axis direction. In this case, the spacer 800 only needs to be positioned in a position where both ends do not protrude from at least one of the two electrode bodies in the Z-axis direction. In other words, both ends of the spacer 800 do not need to protrude from the longer electrode body in the Z-axis direction, and they may protrude from the shorter electrode body. When three or more electrode bodies with different lengths in the Z-axis direction are arranged, it is only necessary that both ends of the spacer 800 do not protrude from the longest electrode body in the Z-axis direction.

In the above embodiment, the sheet member 900 connects the ends of the electrode bodies 600 and 700 in both directions in the Z-axis direction, but it may also be configured to connect the ends of the electrode bodies 600 and 700 in only one direction in the Z-axis direction. Alternatively, the energy storage element may not be equipped with the sheet member 900.

Configurations constructed by any combination of the above embodiments and modifications are also within the scope of the present invention.

The present invention can be applied to energy storage elements such as lithium-ion secondary batteries.

REFERENCE SIGNS LIST 10, 11 Energy storage element 100 Container 110 Container body 111 Long side wall portion 112 Short side wall portion 113 Bottom wall portion 120 Lid body 121 Gas exhaust valve 122, 301, 401, 501 Through hole 200 Electrode terminal 201 Shaft portion 300 Upper gasket 400 Lower gasket 500 Current collector 510 Terminal connection portion 520 Electrode connection portion 600, 700 Electrode body 601, 701 Laminated portion 610, 710 Electrode body main body portion 611, 612, 711, 712 Electrode body flat portion 613, 614, 713, 714 Electrode body curved portion 800 Spacer 900 Sheet member 910, 920 First sheet portion 930, 940 Second seat portion

Claims (8)

A plurality of electrode bodies arranged in a first direction;
a current collector connected to an end portion of each of the plurality of electrode bodies in a second direction perpendicular to the first direction;
electrode terminals arranged in a third direction perpendicular to the first direction and the second direction of the plurality of electrode bodies and connected to the current collectors;
a spacer disposed between two of the plurality of electrode bodies in contact with the two electrode bodies and electrically insulated from the two electrode bodies;
Each of the plurality of electrode assemblies includes an electrode plate and a separator,
the spacer is disposed at a position such that both ends thereof do not protrude from at least one of the plurality of electrode bodies in the third direction;
a portion of the spacer is disposed at a position facing the center in the third direction of at least one of the plurality of electrode bodies. a container having a long side and a short side;
a plurality of electrode assemblies accommodated in the container and arranged in a first direction;
a current collector connected to an end portion of each of the plurality of electrode bodies in a second direction perpendicular to the first direction;
electrode terminals arranged in a third direction perpendicular to the first direction and the second direction of the plurality of electrode bodies and connected to the current collectors;
a spacer that is not disposed between the long side surface of the container and the plurality of electrode bodies, but is disposed between two of the plurality of electrode bodies in a state of contact with the two electrode bodies ;
Each of the plurality of electrode assemblies includes an electrode plate and a separator,
the spacer is disposed at a position such that both ends thereof do not protrude from at least one of the plurality of electrode bodies in the third direction;
a portion of the spacer is disposed at a position facing the center in the third direction of at least one of the plurality of electrode bodies. A plurality of electrode bodies arranged in a first direction;
a current collector connected to an end portion of each of the plurality of electrode bodies in a second direction perpendicular to the first direction;
electrode terminals arranged in a third direction perpendicular to the first direction and the second direction of the plurality of electrode bodies and connected to the current collectors;
a spacer disposed between two of the plurality of electrode bodies and electrically insulated from the two electrode bodies;
a sheet member connecting the ends of the two electrode bodies in the third direction ,
Each of the plurality of electrode assemblies includes an electrode plate and a separator,
the spacer is disposed at a position such that both ends thereof do not protrude from at least one of the plurality of electrode bodies in the third direction;
a portion of the spacer is disposed at a position facing the center in the third direction of at least one of the plurality of electrode bodies. a container having a long side and a short side;
a plurality of electrode assemblies accommodated in the container and arranged in a first direction;
a current collector connected to an end portion of each of the plurality of electrode bodies in a second direction perpendicular to the first direction;
electrode terminals arranged in a third direction perpendicular to the first direction and the second direction of the plurality of electrode bodies and connected to the current collectors;
a spacer that is not disposed between the long side surface of the container and the plurality of electrode bodies but is disposed between two of the plurality of electrode bodies;
a sheet member connecting the ends of the two electrode bodies in the third direction ,
Each of the plurality of electrode assemblies includes an electrode plate and a separator,
the spacer is disposed at a position such that both ends thereof do not protrude from at least one of the plurality of electrode bodies in the third direction;
a portion of the spacer is disposed at a position facing the center in the third direction of at least one of the plurality of electrode bodies. The energy storage element according to claim 3 , wherein the sheet member is arranged by being wrapped around the plurality of electrode bodies so as to surround the entire periphery of the plurality of electrode bodies. Each of the two electrode bodies has a pair of curved portions formed by winding the electrode plate and positioned at both ends in the third direction, and a flat portion connecting the pair of curved portions,
The energy storage element according to any one of claims 1 to 5, wherein the spacer is arranged between the flat portions of the two electrode bodies and is arranged in a position in the third direction such that both ends do not protrude beyond a pair of curved portions of at least one of the two electrode bodies. The energy storage element according to claim 1 , wherein the spacer is shorter than both of the two electrode bodies in the third direction. The energy storage element according to claim 1 , wherein a plurality of the spacers are disposed between the two electrode bodies.