BATTERY AND METHOD OF MANUFACTURING THE SAME

A battery in which an electrode tab group is less likely to be damaged is provided. The battery disclosed herein includes an exterior body, a sealing plate, an electrode body, an electrode body holder, a positive electrode terminal, a negative electrode terminal, a positive electrode current collector, and a negative electrode current collector. The electrode body is fixed to the inner wall surface of the electrode body holder.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is based upon and claims the benefit of priority from Japanese patent application No. 2021-137242 filed on Aug. 25, 2021, and the entire disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE DISCLOSURE

1. Technical Field

The present disclosure relates to a battery and a method of manufacturing the same.

A battery such as a lithium-ion secondary battery generally includes: an electrode body including an electrode; an exterior body having an opening and housing the electrode; a sealing plate sealing the opening of the exterior body; a terminal electrically connected to the electrode inside the exterior body and extending from the sealing plate toward outside of the exterior body; and a current collector electrically connected to the electrode and the terminal. A known configuration of this type of battery is typically such that the electrode is provided with an electrode tab group including multiple electrode tabs for current collection and the electrode is connected to the terminal with the electrode tab group interposed therebetween.

Japanese Patent Application Publication No. 2017-50069 discloses a battery where positive electrode tabs and negative electrode tabs are provided at both ends of an electrode assembly (electrode body) in the width direction. In this document, these electrode tabs are bent along end surfaces of the electrode assembly in the width direction, and bends of the electrode tabs are connected (bonded) to the current collector.

SUMMARY OF THE INVENTION

Vibrations, shock, and the like are applied from the outside to the battery. The electrode tabs are made of, for example, portions of an electrode substrate, and are soft and susceptible to external forces. For example, when external forces are applied to the electrode tab group in the width direction of the electrode body, the electrode body is displaced from a predetermined arrangement position, the electrode tab group (a positive electrode tab group and/or a negative electrode tab group) is drawn in the same direction, or pushed against the electrode body or the inner wall of the exterior body. Such a load on the electrode tab group is undesirable because it is a cause of damage to the electrode tab group. If the electrode tab group is damaged, the electrical connection between the electrode and the terminal may become unstable or poor.

The present disclosure was made in view of the problems, and intended to provide a battery in which the electrode tab group is less likely to be damaged.

According to the technology disclosed herein, provided is a battery including: an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall; a sealing plate sealing the opening; an electrode body housed in the exterior body and including a positive electrode, a negative electrode, and a separator separating between the positive electrode and the negative electrode; an electrode body holder housing the electrode body, made of resin, and housed in the exterior body with the electrode body housed in the electrode body holder; a positive electrode terminal and a negative electrode terminal which are attached to the sealing plate; and a positive electrode current collector which electrically connects between the positive electrode and the positive electrode terminal of the electrode body and a negative electrode current collector which electrically connects between the negative electrode and the negative electrode terminal of the electrode body. The electrode body has a pair of first side surfaces facing the first side walls. At a first end of the electrode body in a facing orientation of the first side surfaces, a positive electrode tab group including multiple positive electrode tabs protruding from the first end is provided. At a second end of the electrode body different from the first end in a facing orientation of the first side surfaces, a negative electrode tab group including multiple negative electrode tabs protruding from the second end is provided. In the positive electrode tab group, the tips of the positive electrode tabs constituting the positive electrode tab group are bent so as to be arranged along one of the second side walls, and portions of the positive electrode tabs bent are bonded to the positive electrode current collector. In the negative electrode tab group, tips of the negative electrode tabs constituting the negative electrode tab group are bent so as to be arranged along the other second side wall, and portions of the negative electrode tabs bent are bonded to the negative electrode current collector. The electrode body is fixed to an inner wall surface of the electrode body holder.

In the battery with this configuration, the electrode body is fixed to the inner wall surface of the electrode body holder. Thus, if external forces such as vibrations and shock are applied to the battery from the outside, movement of the electrode body in the exterior body (specifically, the movement in a facing orientation of the first side surfaces) can be reduced. This allows reduction in load on the electrode tab group due to the movement of the electrode body and reduction in damage to the electrode tab group. The “positive electrode tabs” and “negative electrode tabs” herein may be referred to as “electrode tabs” when no particular distinction is made between positive and negative. The same applies to the “electrode current collector.”

In a preferred aspect, the battery disclosed herein further includes a first adhesive layer between at least one of the first side surfaces of the electrode body and the inner wall surface of the electrode body holder, wherein the electrode body is fixed to the inner wall surface with the first adhesive layer interposed therebetween. In the battery with this configuration, the first adhesive layer is provided in the portion. This efficiently achieves the effect of reducing damage to the electrode tab group.

In another preferred aspect, the first adhesive layer is provided in at least a portion of the inner wall surface of the electrode body holder or at least a portion of the first side surface of the electrode body. This configuration facilitates manufacturing of the battery in addition to the effects.

In another preferred aspect, the separator has an adhesive separator including a substrate and a second adhesive layer provided on at least a portion of the surface of the substrate, and at least a portion of the second adhesive layer constitutes the first side surface, and the electrode body is fixed to the inner wall surface with the second adhesive layer interposed therebetween. This configuration facilitates manufacturing of the battery in addition to the effects. In addition, when the battery includes multiple electrode bodies, displacement of the electrode bodies can be reduced.

In another aspect of the battery disclosed herein, an area of the first adhesive layer or the second adhesive layer is ⅓ or less of the area of the first side surface. This configuration facilitates impregnation of the electrolyte to the electrode body in addition to the effects.

According to the technology disclosed herein, provided is a method of manufacturing a battery including: an exterior body having a bottom wall, a pair of first side walls extending from the bottom wall and facing each other, a pair of second side walls extending from the bottom wall and facing each other, and an opening facing the bottom wall; a sealing plate sealing the opening; an electrode body which is housed in the exterior body and including a positive electrode, a negative electrode, and a separator separating between the positive electrode and the negative electrode and which has a pair of first side surfaces facing the first side walls; an electrode body holder housing the electrode body, made of resin, and housed in the exterior body with the electrode body housed in the electrode body holder; a positive electrode terminal and a negative electrode terminal which are attached to the sealing plate; and a positive electrode current collector which electrically connects between the positive electrode and the positive electrode terminal of the electrode body and a negative electrode current collector which electrically connects between the negative electrode and the negative electrode terminal of the electrode body. The manufacturing method includes: bending a positive electrode tab group provided at a first end of the electrode body in a facing orientation of the first side surfaces and including multiple positive electrode tabs protruding from the first end so that tips of the positive electrode tabs constituting the positive electrode tab group are arranged along one of the second side walls and bonding portions of the positive electrode tabs bent and the positive electrode current collector to each other; bending a negative electrode tab group provided at a second end of the electrode body different from the first end in a facing orientation of the first side surfaces and including multiple negative electrode tabs protruding from the second end so that tips of the negative electrode tabs constituting the negative electrode tab group are arranged along the other second side wall and bonding portions of the negative electrode tabs bent and the negative electrode current collector to each other; housing the electrode body in the electrode body holder with the positive electrode tab group and the negative electrode tab group being bonded to the positive electrode current collector and the negative electrode current collector, respectively; and applying pressure and/or energy to the electrode body holder housing the electrode body and fixing the first side surfaces to the inner wall surface of the electrode body holder.

With this configuration, the electrode body is fixed to the inner wall surface of the electrode body holder. Thus, if external forces such as vibrations and shock are applied to the battery from the outside, movement of the electrode body in the exterior body (specifically, the movement in a facing orientation of the first side surfaces) can be reduced. The above-described manufacturing method allows a battery in which damage to the electrode tab group is reduced to be manufactured.

The manufacturing method preferably includes: forming a first adhesive layer between at least one of the first side surfaces and the inner wall surface of the electrode body holder and fixing the first side surface and the inner wall surface to each other with the first adhesive layer interposed therebetween. With this configuration, the first adhesive layer is formed in the portion. This efficiently achieves the effect of reducing damage to the electrode tab group.

In the manufacturing method, it is preferred that as the separator, an adhesive separator including a substrate and a second adhesive layer provided on at least a portion of the surface of the substrate is used, the first side surface is formed of at least a portion of the second adhesive layer, and the first side surface and the inner wall surface are fixed to each other with the second adhesive layer interposed therebetween. This configuration facilitates manufacturing of the battery in addition to the effects. This further allows a battery which includes multiple electrode bodies and in which displacement of the electrode bodies from each other is reduced to be manufactured.

Further, in another aspect, the manufacturing method disclosed herein further includes: housing the electrode body holder housing the electrode body in the exterior body; and sealing the exterior body with the sealing plate after the housing. The fixation is performed by applying pressure and/or energy to the first side wall of the exterior body after the sealing. With this configuration, damage to the electrode body to which pressure or energy is applied during the fixation can be reduced.

The energy is preferably thermal energy, optical energy, or ultrasonic energy. In the manufacturing method disclosed herein, the energy is applied for the fixation. Thus, a battery having desired effects can be efficiently manufactured.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some preferred embodiments of the technology disclosed herein will be described below with reference to the accompanying drawings. The matters necessary for executing the technology disclosed herein (e.g., the commonly used configuration and manufacturing processes of the battery which does not characterize the technology disclosed herein (the secondary battery in the technology disclosed herein)), except for matters specifically herein referred to can be grasped as design matters of those skilled in the art based on the related art in the preset field. The technology disclosed herein can be executed based on the contents disclosed herein and the technical knowledge in the present field.

The “secondary battery” herein is a term that indicates all electricity storage devices that can be repeatedly charged and discharged, and is a concept that encompasses so-called secondary batteries (chemical batteries) such as a lithium-ion secondary battery and a nickel hydrogen battery and capacitors (physical batteries) such as an electric double layer capacitor. The secondary battery herein is also referred to as simply “battery.”

FIG.1is a perspective view schematically illustrating a battery1according to an embodiment.FIG.2is an exploded perspective view schematically illustrating the battery1according to an embodiment.FIG.3is a schematic sectional view taken along line III-III ofFIG.1. In each drawing which is herein referred to, the reference sign X indicates the “depth direction,” the reference sign Y indicates the “width direction,” and the reference sign Z indicates the “height direction.” In the depth direction X, F indicates “front” and Rr indicates “rear.” In the width direction Y, L indicates “left” and R indicates “right.” In the height direction Z, U indicates “up” and D indicates “down.” Such directions are defined for convenience of explanation and are not intended to limit the installation configuration of the battery1.

As shown inFIGS.1to3, a battery1includes a battery case10, an electrode body20, an electrode body holder29, a positive electrode terminal30, a negative electrode terminal40, a positive electrode current collector50, a negative electrode current collector60, an insulator70, and a gasket90. Although not shown in the drawings, the battery1further includes an electrolyte. The battery1herein is a lithium-ion secondary battery.

The battery case10is a housing for housing the electrode body20. The battery case10herein has a flat, bottomed rectangular (square) outside shape. The material of the battery case10may be the same as commonly used material without particular limitations. The material of the battery case10is preferably metal, and more preferably aluminum, an aluminum alloy, iron, an iron alloy, or the like, for example. The battery case10further houses an electrolyte (not shown) in addition to the electrode body20. As the electrolyte, any electrolyte which can be used in lithium-ion secondary batteries can be used without particular limitations, and the electrolyte does not characterize the technology disclosed herein. Thus, the detailed description thereof is omitted.

The battery case10includes an exterior body12having an opening12hand a sealing plate (lid)14sealing the opening12h. As shown inFIGS.1and2, the exterior body12has a flat rectangular bottom wall12a, a pair of long side walls12bextending from the respective long sides of the bottom wall12ain the height direction Z and facing each other, and a pair of short side walls12cextending from the respective short sides of the bottom wall12ain the height direction and facing each other. Each long side wall12bis an example of the first side wall in the battery disclosed herein. Each short side wall12cis an example of second side wall in the battery disclosed herein. The bottom wall12afaces the opening12h. The area of each short side wall12cis larger than the area of the long side wall12b. The sealing plate14seals the opening12hof the exterior body12. The sealing plate14faces the bottom wall12aof the exterior body12. The sealing plate14has a substantially rectangular shape in plan view. The battery case10is integrated by the sealing plate14bonded to the periphery of the opening12hof the exterior body12. The battery case10is hermetically sealed (airtight).

The sealing plate14is provided with a liquid injection hole15, a gas discharge valve17, and two terminal outlets18and19. The liquid injection hole15is for injecting an electrolyte after assembling of the sealing plate14to the exterior body12. The liquid injection hole15is sealed with a sealing member16. The gas discharge valve17is thin portion configured to be broken and to discharge gas inside the battery case10to the outside when the pressure inside the battery case10exceeds a predetermined value. The terminal outlets18and19are formed in both ends of the sealing plate14in the width direction Y. The terminal outlets18and19penetrate the sealing plate14in the height direction Z. The terminal outlets18and19have inner diameters which allow the positive electrode terminal30and the negative electrode terminal40to be inserted thereinto respectively before being attached to the sealing plate14(before being crimping-processed).

The positive electrode terminal30and the negative electrode terminal40are both attached to the sealing plate14. The positive electrode terminal30is arranged on one side of the sealing plate14in the width direction Y (left side inFIGS.1to3). The negative electrode terminal40is arranged on one side of the sealing plate14in the width direction Y (right side inFIGS.1to3). For the positive electrode terminal30, aluminum or the like is used, for example. For the negative electrode terminal40, copper or the like is used, for example.

The positive electrode terminal30includes a flat plate-like base31arranged on the outer surface of the sealing plate14and a shaft32extending downward (toward the bottom wall12a) from the base31in the height direction Z. The base31of the positive electrode terminal30is exposed on the outer surface of the sealing plate14. The shaft32of the positive electrode terminal30extends from the outside of the sealing plate14through the terminal outlet18. The shaft32is fixed to the positive electrode first current collector51through the through hole of the positive electrode first current collector51of the positive electrode current collector50to be described later inside the battery case10. The positive electrode terminal30is fixed to the periphery surrounding the terminal outlet18of the sealing plate14by crimping (riveting) processing. In the battery1, the negative electrode terminal40also has substantially the same structure as the positive electrode terminal30. Thus, the detailed illustration and description of the structure of the negative electrode terminal40is omitted. InFIG.3, the reference numeral41indicates the base of the negative electrode terminal40, and the reference numeral42indicates the shaft.

A plate-like positive electrode external electroconductive member35and a plate-like negative electrode external electroconductive member45are attached to the outer surface of the sealing plate14. The positive electrode external electroconductive member35is electrically connected to the positive electrode terminal30. The negative electrode external electroconductive member45is electrically connected to the negative electrode terminal40. The positive electrode external electroconductive member35and the negative electrode external electroconductive member45are members to which busbars are attached when multiple batteries1are electrically connected to each other. The positive electrode external electroconductive member35and the negative electrode external electroconductive member45are made of aluminum or an aluminum alloy, for example. The positive electrode external electroconductive member35and the negative electrode external electroconductive member45are insulated from the sealing plate14by an external insulating member92. The positive electrode external electroconductive member35and the negative electrode external electroconductive member45are not essential and can be omitted in other embodiments. As the constituent material for the external insulating member92, resin materials listed as constituent materials for the insulator70and the gasket90to be described later can be used.

The insulator70is arranged between the positive electrode current collector50(specifically, a terminal connection portion51aof the positive electrode first current collector51) and the inner surface of the sealing plate14. The insulator70has a through hole. The gasket90is arranged between the positive electrode terminal30(specifically, the base31) and the outer surface of the sealing plate14. The gasket90has a tubular protrusion inserted into the terminal outlet18of the sealing plate14. The protrusion of the gasket90is arranged along the inner periphery of the through hole of the insulator70. The insulator70and the gasket90having the above-described configurations provided allow reduction in contact between the positive electrode current collector50and the sealing plate14and the contact between the positive electrode terminal30and the sealing plate14. The same insulating structure as that using the insulator and the gasket is also provided in the negative electrode terminal40. Thus, the detailed description thereof is omitted. The constituent material for the insulator70and the gasket90are not particularly limited, and can be resin materials such as polyolefin resins (e.g., polypropylene (PP), polyethylene (PE)) and fluorine resins (e.g., perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE)).

The battery1has one or more electrode bodies20. In the embodiment shown inFIG.2, the battery1includes three electrode bodies20. As shown inFIG.3, the battery1includes a positive electrode current collector50which electrically connects the positive electrode of the electrode body20and the positive electrode terminal30and a negative electrode current collector60which electrically connects the negative electrode of the electrode body20and the negative electrode terminal40, inside the exterior body12.

FIG.4is a schematic view illustrating a configuration of an electrode body20. As shown inFIG.4, the electrode body20includes a positive electrode, a negative electrode, and a separator separating between the positive electrode and the negative electrode (the positive electrode plate22, the negative electrode plate24, and the separator26inFIG.4). The electrode body20herein is a flat wound electrode body configured such that a strip-like positive electrode plate22and a strip-like negative electrode plate24are stacked with a strip-like separator26interposed therebetween, and wound around the winding axis WL. As the constituent material for the positive electrode plate22, the negative electrode plate24, and the separator26, materials used in this kind of lithium-ion secondary batteries can be used without particular limitations. The constituent materials do not characterize the technology disclosed herein. Thus, detailed description thereof is omitted.

The electrode body20includes a pair of wide first side surfaces20aand a pair of second side surfaces20beach having a rectangular portion and two curved portions sandwiching the rectangular portion. As shown inFIGS.1to4, the electrode body20is arranged inside the exterior body12so that the winding axis WL is parallel with the width direction Y. Specifically, the electrode body20is arranged inside the exterior body12so that the winding axis WL is parallel with the bottom wall12aand orthogonal to the short side walls12c. Each first side surface20afaces each long side wall12bof the exterior body12, and each second side surface20bfaces each short side wall12c. At the first end201of the electrode body20in a facing orientation (e.g., the width direction Y inFIGS.1to4) of the first side surfaces20a, a positive electrode tab group23including multiple positive electrode tabs22tprotruding from the first end201is provided. The first end201is an end facing each short side wall12cclose to the positive electrode current collector50(on the left side in the width direction Y inFIG.3). At the second end202of the electrode body20different from the first end201in a facing orientation of the first side surfaces20a, a negative electrode tab group25including multiple negative electrode tabs24tprotruding from the second end202is provided. The second end202is an end facing each short side wall12cclose to the negative electrode current collector60(on the right side in the width direction YinFIG.3).

The positive electrode plate22is, as shown inFIG.4, a long strip-like member. The positive electrode plate22includes a positive electrode collector foil22cand a positive electrode active material layer22afixed to at least one surface of the positive electrode collector foil22c. Although not particularly limited thereto, one side edge of the positive electrode plate22in the width direction Y may be provided with a positive electrode protective layer22p, if necessary.

At one end of the strip-like positive electrode collector foil22cin the width direction Y (left end inFIG.4), multiple positive electrode tabs22tare provided. The positive electrode tabs22tprotrude toward one side in the width direction Y (left side inFIG.4). The positive electrode tabs22tprotrude further in the width direction Y than the separator26. The positive electrode tabs22tare spaced (intermittently) along the longitudinal direction of the positive electrode plate22. The positive electrode tabs22teach have a trapezoid shape. Each positive electrode tab22tis part of the positive electrode collector foil22c, and made of a metal foil (e.g., an aluminum foil). The positive electrode tabs22tare portions (current collector foil exposing portion) of the positive electrode collector foil22cwhere the positive electrode active material layer22aand the positive electrode protective layer22pare not formed. However, the positive electrode tabs22tmay be members separate from the positive electrode collector foil22c.

Similarly to the positive electrode plate22, the negative electrode plate24is also a long strip-like member. As shown inFIG.4, the negative electrode plate24includes a negative electrode current collector foil24cand a negative electrode active material layer24afixed to at least one surface of the negative electrode current collector foil24c.

At one end of the strip-like negative electrode current collector foil24cin the width direction Y (right end inFIG.4), multiple negative electrode tabs24tare provided. The negative electrode tabs24tprotrude toward one side in the width direction Y (right side inFIG.4). The negative electrode tabs24tprotrude further in the width direction Y than the separator26. The negative electrode tabs24tare spaced (intermittently) along the longitudinal direction of the negative electrode plate24. The negative electrode tabs24teach have a trapezoid shape. Each negative electrode tab24tis part of the negative electrode current collector foil24c, and made of a metal foil (e.g., a copper foil). The negative electrode tabs24tare portions (current collector foil exposing portion) of the negative electrode current collector foil24cwhere the negative electrode active material layer24ais not formed. However, the negative electrode tabs24tmay be members separate from the negative electrode current collector foil24c.

By the above-described winding, the positive electrode tabs22tprotruding from the first end201are stacked, thereby forming a positive electrode tab group23.FIG.5is a partial sectional view illustrating bonding between the positive electrode tab group23and the positive electrode current collector50, viewed from the sealing plate14. As shown inFIGS.1to5, the tips of the positive electrode tabs22tconstituting the positive electrode tab group23are bent so as to be arranged along the short side wall12c. By the above-described bending, a positive electrode bend23ais formed in the positive electrode tab group23. Portions of the positive electrode tabs22tbent are bonded to the positive electrode current collector50(specifically, the tab bonding portion52b). Specifically, portions of the positive electrode tabs22tcloser to their tips than the positive electrode bend23aare bonded to the positive electrode current collector50, and a bonding portion J between the positive electrode tabs22tand the positive electrode current collector50is formed. As means for the bonding, ultrasound welding, resistance welding, laser welding, or the like may be used, for example (the same applies to the negative electrode).

By the above-described winding, the negative electrode tabs24tprotruding from the second end202are stacked, thereby forming a negative electrode tab group25. Although detailed illustration is omitted, the tips of the negative electrode tabs24tconstituting the negative electrode tab group25are bent so as to be arranged along the short side wall12c. By the above-described bending, a negative electrode bend is formed in the negative electrode tab group25. Portions of the negative electrode tabs24tbent are bonded to the negative electrode current collector60(specifically, the tab bonding portion62binFIG.12). Specifically, portions of the negative electrode tabs24tcloser to their tips than the negative electrode bend are bonded to the negative electrode current collector60, and a bonding portion between the negative electrode tabs24tand the negative electrode current collector60is formed.

As shown inFIG.3, the positive electrode current collector50includes a positive electrode first current collector51and a positive electrode second current collector52. The positive electrode first current collector51has an L-shaped cross section. The positive electrode first current collector51includes a terminal connection portion51aarranged along the inner surface of the sealing plate14, and a lead portion51bextending from one end of the terminal connection portion51ain the width direction Y toward the bottom wall12a. The terminal connection portion51ahas a through hole at a position corresponding to the terminal outlet18of the sealing plate14. The shaft32of the positive electrode terminal30is inserted into the through hole.

As shown inFIGS.2and3, the positive electrode second current collectors52extends toward the bottom wall12aof the exterior body12. The positive electrode second current collector52includes a first current collector connection portion52aand a tab bonding portion52b. The first current collector connection portion52ais electrically connected to the positive electrode first current collector51. The first current collector connection portion52aextends along the up-down direction Z. The first current collector connection portion52ais arranged substantially perpendicular to the winding axis WL of each electrode body20. The tab bonding portion52bis bonded to the multiple positive electrode tabs22t. The tab bonding portion52bextends along the up-down direction Z. The tab bonding portions52bare arranged substantially perpendicular to the winding axes WL of the electrode body20. The surface of the tab bonding portion52bconnected to the positive electrode tabs22tis arranged substantially parallel with the short side walls12cof the exterior body12.

As shown inFIGS.2and3, the negative electrode current collector60includes a negative electrode first current collector61and a negative electrode second current collector62. The negative electrode first current collector61includes a terminal connection portion61aand a lead portion61b. The negative electrode second current collector62includes a first current collector connection portion62aand a tab bonding portion62b(seeFIG.12). The configuration of the negative electrode current collector60is the same as that of the positive electrode current collector50. Thus, the detailed description thereof is omitted herein.

As shown inFIG.2, the electrode body holder29includes a rectangular bottom surface291, a pair of wide surfaces292extending from the bottom surface291and facing each other, and a pair of narrow surfaces294extending from the bottom surface291and facing each other. The electrode body holder29has an internal space29shousing the electrode body20, and has an opening29hcommunicating with the internal space29s. The electrode body20is housed in the internal space29sof the electrode body holder29. The electrode body holder29houses a positive electrode tab group23, a positive electrode current collector50bonded to the positive electrode tab group23, a negative electrode tab group25, and a negative electrode current collector60bonded to the negative electrode tab group25. With the electrode body20housed in the internal space29sof the electrode body holder29, the first side surface20afaces the wide surfaces292, and the second side surface20bfaces the narrow surfaces294. At this time, the positive electrode second current collector52of the positive electrode current collector50and the negative electrode second current collector62of the negative electrode current collector60(seeFIG.12) face the narrow surfaces294. With the electrode body holder29housed in the exterior body12, the wide surfaces292of the electrode body holder29face the long side walls12bof the exterior body12, the narrow surfaces294face the short side walls12c, and the bottom surface291faces the bottom wall12a.

Although not particularly limited thereto, the electrode body holder29used may be obtained by bending and molding, for example, a resin film (e.g., a resin film such as polypropylene (PP)).FIG.6is a development view of the electrode body holder29used in an embodiment. As shown inFIG.6, in the developed state, the electrode body holder29includes a bottom surface291, a pair of wide surfaces292extending from a pair of longer sides of the bottom surface291facing each other, a pair of bottom surface adjacent portions293extending from a pair of shorter sides of the bottom surface291facing each other, and narrow surface forming portions29ato29dextending from short sides of the wide surfaces292. The electrode body holder29is molded by bending it in the same direction along the dotted lines inFIG.6.

In the electrode body holder29molded as described above, one narrow surface294is formed of narrow surface forming portions29aand29band a bottom surface adjacent portion293. Specifically, for example, first, the bottom surface adjacent portion293is bent. Subsequently, the narrow surface forming portion29ais bent over the bottom surface adjacent portion293bent. Then, the narrow surface forming portion29bis bent over the narrow surface forming portion29abent. Accordingly, one narrow surface294is formed. At this time, the resin film shown inFIG.6is bent so that the bottom surface adjacent portion293, the narrow surface forming portion29a, and the narrow surface forming portion29bare overlaid in this order from the inside to the outside of the electrode body holder29. The other narrow surface294is formed of narrow surface forming portions29cand29dand a bottom surface adjacent portion293. Specifically, for example, first, the bottom surface adjacent portion293is bent. Subsequently, the narrow surface forming portion29cis bent over the bottom surface adjacent portion293bent. Then, the narrow surface forming portion29dis bent over the narrow surface forming portion29abent. Accordingly, the other narrow surface294is formed. At this time, the resin film is bent so that the bottom surface adjacent portion293, the narrow surface forming portion29c, and the narrow surface forming portion29dare overlaid in this order from the inside to the outside of the electrode body holder29.

In the battery1, the electrode body20is fixed to the inner wall surface of the electrode body holder29. Since the electrode body20is fixed to the inner wall surface of the electrode body holder29, if external forces such as vibrations and shock are applied to the battery1, movement of the electrode body in the exterior body (specifically, the movement in the width direction Y) can be reduced. This allows reduction in load on the electrode tabs due to the movement of the electrode body and reduction in damage to the electrode tab group. With this configuration, an effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group can be achieved.

The means for the fixing can be, for example, forming an adhesive layer having adhesiveness.FIG.7is a partial sectional view illustrating the state in which the electrode body20is fixed to the inner wall surface of the electrode body holder29, viewed from the sealing plate14of the battery1according to an embodiment. InFIG.7, illustration of the exterior body12and the sealing plate14is omitted. As shown inFIGS.2and7, the battery1includes a first adhesive layer100between the first side surface20aof the electrode body20and the inner wall surface of the electrode body holder29(specifically, the inner surface of one or both wide surfaces292of the electrode body holder29, both inFIG.7), and the electrode body20is fixed to the inner wall surface with the first adhesive layer100interposed therebetween. The first adhesive layer100is provided in two electrode bodies facing the wide surfaces292of the electrode body holder29among the three electrode bodies housed in the electrode body holder29. With the first adhesive layer100formed on this portion, an effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group can be achieved.

Although not particularly limited thereto, the first adhesive layer100is preferably provided in at least part of the inner wall surface (e.g., the inner surfaces of the wide surfaces292) of the electrode body holder29.FIG.8is a development view of the electrode body holder29shown inFIG.7. Specifically, as shown inFIG.8, for example, the first adhesive layer100is provided by, for example, applying a material for forming the first adhesive layer100(e.g., a slurry, a paste, and the like containing a resin material to be described later) to the wide surface292of the resin film before molding, then drying the material, as appropriate, and subjecting the material to a predetermined process, or the first adhesive layer100may be provided by means of adhering an adhesive tape (including pressure-sensitive adhesive tape. Thus, an electrode body holder29including a first adhesive layer100on the wide surface292can be produced. With the first adhesive layer100provided in the electrode body holder29, an effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group can be achieved. In addition, formation of the first adhesive layer100in the electrode body20can be omitted. Further, for example, the risk of contact with the first adhesive layer100during the manufacturing process can be reduced. How to provide the first adhesive layer100in the electrode body holder29will be described in detail later.

As the constituent material for the first adhesive layer100, various resin materials having adhesiveness (or adhesion), which are used as a binder in this kind of secondary battery can be used. Examples of the resin material include: fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE); an acrylic resin; a polyamide resin; a polyimide resin; and polyurethane resin. In order to facilitate the manufacturing of the battery1, various adhesives (pressure-sensitive adhesives) may be suitably used as the constituent material for the first adhesive layer100. Examples of the adhesive include acryl adhesives, rubber-based adhesives, silicone-based adhesives, and urethan-based adhesives. Alternatively, the resin material may be a photocurable resin (e.g., a photocurable acrylic resin) or a thermosetting resin (e.g., a thermosetting acrylic resin).

A region of the wide surface292of the electrode body holder29where the first adhesive layer100is formed (hereinafter also referred to as a “first adhesive layer forming region”) is not particularly limited as long as the effects of the technology disclosed herein can be achieved. As an example, as shown inFIG.8, the central region including the point P of intersection between the center line CL1of the wide surfaces292in the long side direction and the center line CL2of the wide surfaces292in the shorter side can be the first adhesive layer forming region. The area of the central region (i.e., the first adhesive layer forming region) can be, for example, ½ or less, ⅓ or less, ¼ or less, or ⅕ or less of the area of the first side surface20aof the electrode body20. In light of efficient impregnation of the electrolyte into the electrode body20, the area of first adhesive layer forming region is preferably ⅓ or less of the area of the first side surface20a. As described above, the central region needs only include the point P of intersection, and the center of the central region and the point P of intersection may not coincide with each other. In light of the impregnation of the electrolyte into the electrode body20, the center of the central region may be closer to the opening29h(i.e., the side opposite to the bottom surface291, also seeFIG.2) than the point P of intersection. The area of the first adhesive layer forming region means the area of one first side surface20a.

Alternatively, the first adhesive layer forming region may be a region near the electrode tab group.FIG.9is a development view illustrating an example of a portion of the electrode body holder29of the battery1according to an embodiment where the adhesive layer100is provided. In the resin film shown inFIG.9, the region near the electrode tab group which is located closer to the electrode tabs than the center line CL1of the wide surface292in the long side direction after forming the electrode body holder29can be the first adhesive layer forming region. For example, forming a first adhesive layer100in a region near the positive electrode tab group is preferred when the positive electrode tabs22tare made of materials that are more easily damaged than the material for the negative electrode tabs24t. The first adhesive layer100may be formed in a region near the negative electrode tab group, or in both of the region near the positive electrode tab group and a region near the negative electrode tab group, or in another region where the formation is desired such as the central region in addition to the region near the electrode tabs. If the first adhesive layer100is provided in multiple portions, the sum of the areas of the first adhesive layer forming regions may be set within the above-described range.

On the other hand, although detailed illustration is omitted, the first adhesive layer100may be provided on at least a portion of the first side surface20aof the electrode body20. Specifically, the first adhesive layer100may be provided by the following means: applying a material for forming the first adhesive layer100(e.g., a slurry or a paste containing the resin material to be described later) to a predetermined portion of the first side surface20aof the electrode body20before inserted into the electrode body holder29, then drying the material, as appropriate, and subjecting the material to a predetermined process; or adhering an adhesive tape (including a pressure-sensitive adhesive tape); or the like, for example. Also in this case, the effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group can be achieved. The first adhesive layer100provided in the portion allows omission of the first adhesive layer100arranged in the electrode body holder29. Thus, the resin films before forming the electrode body holder29in the manufacturing can be stacked. The first adhesive layer forming region on the first side surface20ais only necessary to match the region on the wide surface292of the electrode body holder29after housing the electrode body20. The area of the first adhesive layer100may be the same as that when the first adhesive layer100is provided on the wide surface292of the electrode body holder29.

If the adhesiveness between the electrode body20and the electrode body holder29is desired to be improved, the first adhesive layer100may be provided on both the first side surface20aof the electrode body20and the inner surface of the wide surface292of the electrode body holder29. InFIG.7, the first adhesive layer100is provided between the inner surface of each wide surfaces292and the first side surface20a. However, the first adhesive layer100may be provided on one side if the effect of the technology disclosed herein can be sufficiently achieved.

OTHER EMBODIMENTS

In the above-described embodiment, a separate adhesive layer (i.e., the first adhesive layer100) is provided between the first side surface20aof the electrode body20and the inner wall surface (the inner surface of the wide surfaces292) of the electrode body holder29. Thus, the fixation between the electrode body20and the electrode body holder29is achieved. However, the fixation is not limited thereto. For example, the fixation can be achieved by using a separator (hereinafter referred to as an “adhesive separator”) including an adhesive layer as part of the separator26of the electrode body20.FIG.10is a partial sectional view illustrating a configuration of the adhesive separator27used in the battery1according to an embodiment. Specifically, the battery1according to the present embodiment includes, as at least a portion of the separator26shown inFIG.4, an adhesive separator27including a substrate27aand a second adhesive layer27bprovided on at least part of the surface of the substrate27a. Here, at least part of the second adhesive layer27bconstitutes the first side surface20a, and the electrode body20is fixed to the inner wall surface of the electrode body holder29with the second adhesive layer27binterposed therebetween. This achieves an effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group. This further allows omission of the process of providing a separate adhesive layer100on the first side surface20aor the inner wall surface of the electrode body holder29. Further, the adhesive layer100is not formed on the inner wall surface of the electrode body holder29. Thus, the resin films before forming the electrode body holder29in the manufacturing can be stacked. If the battery1includes multiple electrode bodies20, the second adhesive layer27bof the adhesive separator27allows improvement in adhesiveness between the electrode bodies20, and allows reduction in displacement from each other.

The substrate27aof the adhesive separator27may be, for example, fine porous thin film, woven fabric, and nonwoven fabric. The constituent material for the substrate can be, for example, preferably polyethylene, polypropylene, and polyolefins such as a copolymer of polyethylene and a olefin. The substrate27amay have a monolayer structure, or a multilayer structure (e.g., polyethylene/polypropylene/polyethylene).

The second adhesive layer27bmay be formed on both surfaces or one surface of the substrate27a(inFIG.10, both surfaces). Here, in the electrode body20shown inFIG.4, when the positive electrode plate22, the negative electrode plate24, and the separator26are stacked and then wound, the outermost layer of the electrode body20is the separator26. Thus, at least, the separator26constituting the outermost layer may be replaced with the adhesive separator27, and the winding may then be performed so that the adhesive separator27is arranged such that the second adhesive layer27bis the outermost layer of the members in the electrode body20in the stacking direction (i.e., the outermost layer of the electrode body20after winding). Although not particularly limited thereto, the second adhesive layer27bmay be formed substantially over the entire surface of the substrate27a. In other words, the area of the second adhesive layer27bon the first side surface20amay be substantially the same as the area of the first side surface20a. Accordingly, the adhesive separator27and the positive electrode active material layer22aare adhered to each other with the second adhesive layer27binterposed therebetween after the winding. In addition to the effect of reducing movement of the electrode body and the effect of reducing damage to the electrode tab group, the effect of reducing a distance between the positive and negative electrodes, the effect of reducing deformation of the electrode body20can be achieved. Similarly to the first adhesive layer100, the second adhesive layer27bmay be formed such that the area of the second adhesive layer27bon the first side surface20ais ½ or less, ⅓ or less, ¼ or less, or ⅕ or less of the area of the first side surface20a.

As the constituent material for the second adhesive layer27b, various resin materials having adhesion (or adhesiveness) can be used. Examples of the resin material include: fluorine resins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

In light of further improving the state of fixation between the electrode body20and the electrode body holder29, the adhesive separator27may be used as a separator constituting the outermost layer of the electrode body20, and the adhesive layer100of the embodiment may be provided on the inner wall surface of the electrode body20and/or the electrode body holder29.

The means of the fixation is not limited to formation of the adhesive layer100and the use of the adhesive separator27, and other means may be employed. For example, as will be described later, the first side surface20aof the electrode body20and the wide surface292of the electrode body holder29may be fixed to each other by ultrasonic bonding. In this case, weld marks of the ultrasonic bonding can be present on at least part of the outer surface of the wide surface292.

<<Method of Manufacturing Battery1>>

FIG.11is a diagram illustrating a method of manufacturing a battery1according to an embodiment.FIGS.12to14are perspective views illustrating steps of the method of manufacturing the battery1according to an embodiment. In the method of manufacturing the battery1, first, a battery case10(an exterior body12and a sealing plate14), an electrode body20(one or more, e.g., three), an electrolyte, an electrode body holder29, a positive electrode terminal30, a negative electrode terminal40, a positive electrode current collector50, and a negative electrode current collector60are provided. Then, as shown inFIG.11, a sealing plate providing step S1, an electrode tab group bonding step S2, an electrode body holder housing step S3, a fixing step S4, and an exterior body housing step S5are performed, thereby manufacturing a battery1. The manufacturing method disclosed herein may further include other processes at any stage. In the following description, reference is made toFIGS.1-14, as appropriate.

In the sealing plate providing step S1, a positive electrode terminal30, a negative electrode terminal40, a positive electrode current collector50, and a negative electrode current collector60are attached to the sealing plate14, and then, the sealing plate14is provided in a state where the electrode body20can be attached. Specifically, first, a positive electrode terminal30, a positive electrode first current collector51, a negative electrode terminal40, a negative electrode first current collector61, and an insulator70are attached to the sealing plate14. The positive electrode terminal30, the positive electrode first current collector51, and the insulator70are fixed to the sealing plate14by crimping processing (riveting), for example. The crimping processing is performed such that, as shown inFIG.3, a gasket90is sandwiched between the outer surface of the sealing plate14and the positive electrode terminal30, and an insulator70is sandwiched between the inner surface of the sealing plate14and the positive electrode first current collector51. Specifically, the positive electrode terminal30before crimping processing is inserted, from above the sealing plate14, into the through hole of the gasket90, the terminal outlet18of the sealing plate14, the through hole of the insulator70, and the through hole of the positive electrode first current collector51in this order to protrude downward the sealing plate14. Then, a portion of the positive electrode terminal30protruding downward from the sealing plate14is crimped so that a compressive force is applied against the up-down direction Z. In this manner, the gasket90, the sealing plate14, the insulator70, and the positive electrode first current collector51are fixed integrally to the sealing plate14. The negative electrode side is similar to the positive electrode side. Thus, detailed description thereof is omitted.

In the electrode tab group bonding step S2, the electrode tab group corresponding to the electrode current collector of the sealing plate14provided in the sealing plate providing step S1is bonded so that the sealing plate14is integral with the electrode body20. Specifically, first, as shown inFIG.12, three electrode bodies20each with the positive electrode second current collectors52and the negative electrode second current collector62are provided. Then, the three electrode bodies20are arranged along the short side direction X (seeFIG.2). At this time, the three electrode bodies20are arranged so that the positive electrode second current collector52is arranged on one side in the long side direction Y (left side inFIG.2), and the negative electrode second current collector62is arranged on the other side in the long side direction Y (right side inFIG.2).

Subsequently, the positive electrode tab group23which has been integrated with the positive electrode second current collectors52is bent. Specifically, the tips of the positive electrode tabs22tconstituting the positive electrode tab group23are bent. Then, with the positive electrode tab group23bent, the positive electrode second current collectors52(first current collector connection portion52a) is bonded to the lead portion51bof the positive electrode first current collector51fixed to the sealing plate14provided in the step S1. The bonding method used can be, for example, welding such as ultrasound welding, resistance welding, and laser welding. The negative electrode side is similar to the positive electrode side. Thus, detailed description thereof is omitted. In this manner, three electrode bodies20are bonded to the sealing plate14. Thus, an integrated body2of the electrode bodies20and the sealing plate14is obtained such as shown inFIG.2.

In the electrode body holder housing step S3, the integrated body2prepared in the electrode tab group bonding step S2is housed in the electrode body holder29. Here, the electrode bodies20are housed in the electrode body holder29with the positive electrode tab group23and the negative electrode tab group25being bonded to the respective current collectors. Specifically, for example, the resin film shown inFIG.8or9is bent as described above, thereby producing a bag-shaped (box-shaped) electrode body holder29. The integrated body2is inserted into the electrode body holder29so that the first side surfaces20aof the electrode bodies20face the wide surfaces292of the electrode body holder29(seeFIG.13). The integrated body2may be produced by stacking the electrode bodies20on the resin film before molding so that the first side surfaces20aface the wide surfaces292and wrapping it.

In the fixing step S4, pressure and/or energy is applied to the electrode body holder29housing the electrode bodies20and fixing the first side surface20ato the inner wall surface of the electrode body holder29. As described above, first adhesive layer100is provided on at least a portion of the wide surface292in the resin film shown inFIG.8or9. The pressure and/or energy may be applied to the first adhesive layer forming region (e.g., a region surrounded by a double-dotted line inFIG.13, see alsoFIG.8) from the outer surface of the wide surface292of the electrode body holder29. The magnitude of pressure, type of energy, and amount of energy can be changed, as appropriate, depending on the size of the first adhesive layer forming region, the constituent material of the first adhesive layer100, and the constituent material of the electrode body20. For example, if the first adhesive layer100is made of an adhesive (pressure-sensitive adhesive), the fixation through the first adhesive layer100can be achieved by applying pressure to the region. The magnitude of the pressure is not particularly limited as long as the fixation through the first adhesive layer100is realized, and may be between 0.01 kgf/cm2and 0.05 kgf/cm2, for example, or about finger pressure. If necessary, heating (e.g., between 40° C. to 60° C.) may be performed when the pressure is applied.

For example, when the first adhesive layer100is formed using thermosetting resin or other resin material, it is preferable to apply heat (e.g., between 60° C. to 70° C.) while applying a predetermined magnitude of pressure (e.g., between 0.05 kgf/cm2to 0.2 kgf/cm2) to apply thermal energy for curing or heat-weld the resin. The temperature at the time of the heating can be changed, as appropriate, depending on the type of resin material used. When the first adhesive layer100is formed using photocurable resin, it is preferable to apply optical energy to cure the resin while applying a predetermined magnitude of pressure (e.g., between 0.01 kgf/cm2and 0.1 kgf/cm2). The type (wavelength) of light applied is not particularly limited, and it depends on the type of photocurable resin. For example, if the photocurable resin is ultraviolet light curable resin, ultraviolet light may be applied. Alternatively, if the photocurable resin is resin cured by visible light, visible light with a wavelength at which the resin can be cured may be applied. If the first adhesive layer100is formed of thermosetting resin or photocurable resin, application of the pressure may be omitted.

When the fixing step S4is performed before the exterior body housing step S5to be described later, the bonding state between the electrode bodies20and the electrode body holder29can be visually checked. Further, the pressure on the exterior body12and the damage due to the thermal energy can be reduced.

In the exterior body housing step S5, the electrode bodies20which have been fixed to the inner wall surfaces of the electrode body holder29by the fixing step S4are housed in the exterior body12(seeFIG.2). Then, the sealing plate14is bonded to the edge of the opening12hof the exterior body12to seal the opening12h. The exterior body12and the sealing plate14are preferably bonded to each other by welding. The bonding by welding can be performed by, for example, laser welding. An electrolyte is then injected through a liquid injection hole15, and the liquid injection hole15is closed by the sealing member16. Thus, a battery1is sealed. In this manner, a battery1can be manufactured.

Other Embodiments

In the above-described embodiment, the fixing step S4is performed before the exterior body housing step S5, but is not limited thereto. In other words, the fixing step may be performed after the exterior body housing step. Specifically, after the electrode body20is housed in the electrode body holder29in the above electrode body holder housing step S3, this electrode body holder29is housed in the exterior body12without applying pressure or energy. Thereafter, the opening12hof the exterior body12is sealed with the sealing plate14. After the sealing, pressure and/or energy (e.g., thermal energy) is applied to a predetermined region of the long side wall12bof the exterior body12(including the region where the adhesive layer100is formed, e.g., the region surrounded by a double-dotted line inFIG.14), so that the electrode bodies20and the electrode body holder29are fixed to each other. When the fixing step is performed after the exterior body housing step, damage to the electrode tab group due to application of pressure or energy can be reduced. Various conditions for the pressure and the energy are the same as described in the embodiment. Thus, the description thereof is omitted.

In the embodiment, electrode body holder29in which the adhesive layer100is formed is used, but is not limited thereto. In other words, an adhesive separator27may be used. In this case, an adhesive separator27including a substrate27aand a second adhesive layer27bprovided in at least a portion of the surface of the substrate27ais used as a portion of the separator constituting the battery1to be manufactured, at least a portion of the second adhesive layer27bconstitutes the first side surface20a, and the first side surface20aand the inner wall surface of the electrode body holder29are fixed to each other with the second adhesive layer27binterposed therebetween. The magnitude of pressure applied during the fixation can be, for example, between 0.1 kgf/cm2and 0.2 kgf/cm2. The temperature for the heating during the fixation can be any temperature at which it is possible to perform thermal welding by the resin material constituting the second adhesive layer, and is, for example, between 60° C. and 80° C.

Alternatively, the first side surface20aof the electrode body20and the inner wall surface of the electrode body holder29may be fixed to each other by applying ultrasonic energy. In this case, formation of the first adhesive layer100and the use of the adhesive separator27can be omitted. When ultrasonic energy is applied to the wide surfaces292of the electrode body holder29while applying pressure to the region to be fixed by using a commercially available device, the fixation can be achieved (e.g., see a region surrounded by a double-dotted line inFIG.13). If a material for which application of thermal energy is undesirable is used as the constituent material for the electrode body20, it is preferred to apply ultrasonic energy to achieve the fixation. By changing the frequency of the ultrasound, as appropriate, only the fixation of the first side surface20a(separator) of the electrode body20and the inner wall surface of the electrode body holder29to each other can be achieved without causing damage to the constituent material for the electrode body20, for example.

Although specific examples of the technology disclosed herein have been described in detail above, they are mere examples and do not limit the appended claims. The technology described in the appended claims include various modifications and changes of the foregoing specific examples.