ELECTRIC STORAGE DEVICE

The electric storage device of the present disclosure includes a case including an exterior package having a first surface formed in a wide width rectangular shape, having a pair of opposed second surfaces, having a pair of opposed third surfaces, and having an opening, and including a sealing plate configured to seal the opening and formed in a wide width rectangular shape. A positive electrode and a negative electrode include plural tabs protruding at one of end parts in a winding axis direction of the electrode body, and include a penetration hole at one surface of the second surface, a terminal is inserted into a penetration hole, wide width surfaces of the electrode body respectively face the sealing plate and the first surface, the tab is arranged inside the case to face the second surface, and a metal joint configured to connect the terminal and the tab is provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2023-021856 filed on Feb. 15, 2023. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND

The present disclosure relates to an electric storage device.

Conventionally, the electric storage device is known that includes an electrode body having a pair of opposed wide width surfaces, includes a case configured to accommodate the electrode body, and includes a terminal electrically connected to the electrode body. For example, Japanese Patent Publication 2022-44958 discloses a battery (an electric storage device) including an electrode body, a battery case (a case), and an electrical collector terminal, which is a technique having an object to implement a space efficiency in the case and to suppress a breakage on an electrode electrical collector body (tab) portion.

SUMMARY

Based on an intensive study of the inventor, there is a room for improvement in the above described conventional technique. As described in detail, the above described electric storage device includes the electrical collector terminal (below, referred to as “electrical collector body”, too), and thus a number of parts is increased so as to cause an increase in an electric resistance.

A herein present disclosure has been made in view of the above-described circumstances, and the object is to provide an electric storage device that can compatibly implement enhancing the space efficiency and suppressing the increase in the electric resistance.

Solution to Problem

A herein disclosed electric storage device includes an electrode body in which a long sheet-shaped positive electrode and a long sheet-shaped negative electrode are wound in a sheet longitudinal direction via a separator and which has a pair of opposed wide width surfaces, includes a case which is formed in a hexahedron shape, which is configured to accommodate the electrode body, and which has an exterior package having a first surface formed in a wide width rectangular shape, an opening opposed to the first surface, a pair of opposed second surfaces extending from an outer edge of the first surface to the opening, a pair of opposed third surfaces extending from the outer edge of the first surface to the opening, and has a sealing plate configured to seal the opening, opposed to the first surface, and formed in a wide width rectangular shape, and includes terminals electrically connected to the electrode body. Here, each of the positive electrode and the negative electrode includes plural tabs protruding at one of end parts in a winding axis direction of the electrode body, penetration holes are provided on one of the second surfaces, the terminals are inserted into the penetration holes, the electrode body is arranged inside the case, wherein the wide width surfaces respectively face the sealing plate and the first surface, and to make the tabs face the second surfaces to which the terminals are attached, and a metal joint is provided to connect the terminals and the tabs.

According to the configuration described above, the tab of the electrode body and the terminal are directly and electrically connected by the metal joint without an electrical collector body, and thus it is possible to suppress the increase in the electric resistance. Further, by using the case configured as described above, it is possible to easily accommodate the electrode body in the case. By doing this, it is possible to further increase a volume of the electrode body. By increasing the volume of the electrode body, a movable range of the electrode body in the case is reduced. By doing this, it is possible to suitably reduce the breakage risk on the tab. Accordingly, it is possible to compatibly implement the capacity enhancement of the electric storage device (high volume energy density) and the conduction reliability.

DETAILED DESCRIPTION

Below, while referring to figures, an embodiment in accordance with a herein present disclosure will be explained. Incidentally, a matter not described in the present specification but required for performing the herein present disclosure can be grasped as design matters of those skilled in the art based on the related art in the present field. The herein present disclosure can be executed based on the contents disclosed in the present specification, and the technical common sense in the present field. Additionally, in the following accompanying figures, the same numerals and signs are given to the members/parts providing the same effect. Additionally, in each figure, the dimensional relation (a length, a width, a thickness, or the like) may not reflect the actual dimensional relation. Incidentally, a numerical value range expressed as “A to B” in the present specification semantically includes A and B, and semantically covers meanings of “preferably more than A” and “preferably less than B”.

A term “electric storage device” in the present specification means a device that can perform charging and discharging. The electric storage device semantically covers a battery referred to generally as a lithium ion battery, a lithium secondary battery, or the like, and further covers a lithium polymer battery, a lithium ion capacitor, and the like. The secondary battery means a battery in general that is capable of repeatedly charging and discharging according to a movement of a charge carrier between a positive electrode and a negative electrode. Here, as one form of the electric storage device, a lithium ion secondary battery is illustrated.

FIG.1is a perspective view that schematically shows an electric storage device1in accordance with one embodiment.FIG.2is a longitudinal cross section view that is schematically shown along a II-II line ofFIG.1.FIG.3is a longitudinal cross section view that is schematically shown along a III-III line ofFIG.1. InFIG.3, for convenience sake of explanation, the number of negative electrode tabs24tis represented as11, but the herein present disclosure is not restricted to this. Incidentally, in an explanation described below, reference signs L, R, F, Rr, U, and D in the figures respectively represent left, right, front, rear, up, and down (in a gravity direction). Additionally, in the figures, a reference sign X represents a short side direction (referred to as a thickness direction, too) of the electric storage device1, a reference sign Y represents a long side direction of the electric storage device1, and a reference sign Z represents a vertically direction (referred to as a height direction, too). However, these are merely directions for convenience sake of explanation, which never restricts the disposed form of the electric storage device1.

As shown inFIG.1andFIG.2, the electric storage device1includes a case10, an electrode body20, a positive electrode terminal30, and a negative electrode terminal40. As the illustration is omitted, the electric storage device1herein further includes an electrolytic solution. It is preferable that the electric storage device1is a nonaqueous electrolyte secondary battery, such as lithium ion secondary battery.

The case10is, for example, a member formed in a hexahedron shape and configured to accommodate the electrode body20. As shown inFIG.1andFIG.2, the case10includes an exterior package12and a sealing plate14. The case10is typically made of a metal, such as aluminum, aluminum alloy, and stainless steel.

The exterior package12is, for example, a main body of the case10which is configured to accommodate the electrode body20at the inside. As shown inFIG.1and FIG.2, the exterior package12includes an opening12h, a first surface12a, a pair of opposed second surfaces12b,12c, and a pair of opposed third surfaces12d,12e. In this embodiment, the first surface12ais formed in a wide width rectangular shape, and is opposed to the opening12h. In addition, a pair of second surfaces12b,12crespectively extend from a pair of opposed long sides of the first surface12a. As shown inFIG.1andFIG.2, the second surface12c, which is positioned at a lower side, configures a bottom surface of the electric storage device1. In addition, the second surface12b, which is positioned at an upper side, is an upper surface opposed to this bottom surface, and herein is an attaching surface with the positive electrode terminal30and the negative electrode terminal40. In addition, a pair of third surfaces12d,12erespectively extend from a pair of opposed short sides of the first surface12a. Incidentally, in the present specification, the term “rectangular shape” semantically covers a shape in which the long side formed in a straight line shape and a short side formed in a straight line shape are joined to each other via a curved line, a shape in which at least one of the long side and the short side is formed in a not-straight line shape but is bent, concaved and convexed, or curved so as to be configured with plural straight lines or with curved lines, and the like.

The opening12his a portion, for example, on which the sealing plate14is attached. Here, the opening12his surrounded by upper ends of the pair of second surfaces12b,12cand upper ends of the pair of third surfaces12d,12e, so as to be formed in a wide width rectangular shape. As shown inFIG.3, the opening12his provided with a recessed step121along an inner end. Here, the sealing plate14is fit into the step121. In addition, by welding the sealing plate14to the step121of the exterior package12, the exterior package12and the sealing plate14are integrated so as to make the case10be sealed airtightly.

As shown inFIG.2, the second surface12bis provided with an exhaust valve123, a liquid injection hole16, a first terminal attaching part124, and a second terminal attaching part125. The exhaust valve123is, for example, a thin-walled part. Here, the exhaust valve123is configured to be broken when a pressure inside the case10becomes equal to or more than a predetermined value, so as to exhaust a gas inside the case10toward an outside. The liquid injection hole16is a penetration hole for performing a liquid injection of the electrolytic solution to the inside of the case10after the sealing plate14is assembled to the exterior package12. The liquid injection hole16here is sealed by a sealing member16aafter the liquid injection of the electrolytic solution. The first terminal attaching part124is, for example, a portion to which the positive electrode terminal30is attached. On a form shown inFIG.2, the first terminal attaching part124is a step recessed from the second surface12b. On a bottom of the first terminal attaching part124, a penetration hole18is provided into which the positive electrode terminal30is inserted. The second terminal attaching part125is, for example, a portion to which the negative electrode terminal40is attached. On the form shown inFIG.2, the second terminal attaching part125is a step recessed from the second surface12b. On a bottom of the second terminal attaching part125, a penetration hole19is provided into which the negative electrode terminal40is inserted.

The sealing plate14is, for example, a member formed in a flat plate shape and is configured to seal the opening12h. Thus, it is good that a shape of the sealing plate14is a shape according to a shape of the opening12h. In this embodiment, the sealing plate14is formed in a wide width rectangular shape. Here, when the sealing plate14is attached to the opening12h, the sealing plate14is opposed to the first surface12a.

As the electrolytic solution, it is possible to use conventionally known one without particular restriction. As one example, a nonaqueous electrolytic solution is preferably used in which a supporting salt (electrolyte salt) is dissolved into a nonaqueous type solvent (organic solvent). As one example of the nonaqueous type solvent, it is possible to use a carbonate type solvent, such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. As one example of the supporting salt, it is possible to use a fluorine-containing lithium salt, such as LiPF6. The electrolytic solution may contain an additive agent as needed.

The positive electrode terminal30is a member electrically connected to a positive electrode22of the electrode body20. As shown inFIG.2, the positive electrode terminal30is inserted into the penetration hole18so as to be exposed to an outer side of the exterior package12. Here, the positive electrode terminal30includes a shaft part30aand a base part30b. The shaft part30ais, for example, formed in a cylindrical shape and is a portion inserted into the penetration hole18. The base part30bis, for example, formed in a flat plate shape, and is a portion arranged along an outer side surface (the second surface12b) of the exterior package12. As shown inFIG.2, the positive electrode terminal30herein is caulked by a caulking process to a circumferential edge portion surrounding the penetration hole18of the exterior package12, and a caulking part is formed inside the exterior package12at an end part of the shaft part30a. It is preferable that the positive electrode terminal30is made of metal, and it is further preferable that the positive electrode terminal is made of, for example, aluminum or aluminum alloy. Incidentally, the positive electrode terminal30is an example for the herein disclosed “terminal”.

The negative electrode terminal40is a member electrically connected to a negative electrode24of the electrode body20. As shown inFIG.2, the negative electrode terminal40is inserted into the penetration hole19so as to be exposed to the outer side of the exterior package12. Here, the negative electrode terminal40includes a shaft part40aand a base part40b. The shaft part40ais, for example, formed in a cylindrical shape and is a portion inserted into the penetration hole19. The base part40bis, for example, formed in a flat plate shape, and is a portion arranged along the outer side surface (the second surface12b) of the exterior package12. As shown inFIG.2, the negative electrode terminal40herein is caulked by the caulking process to a circumferential edge portion surrounding the penetration hole19of the exterior package12, and a caulking part is formed inside the exterior package12at an end part of the shaft part40a. It is preferable that the negative electrode terminal40is made of metal, and it is more preferable that the negative electrode terminal is made of, for example, copper or copper alloy. Incidentally, the negative electrode terminal40is an example for the herein disclosed “terminal”.

Each of the positive electrode terminal30and the negative electrode terminal40is insulated from the exterior package12by a gasket92and an inside insulating member93. The gasket92herein has a function of establishing an insulation of the exterior package12from the positive electrode terminal30and the negative electrode terminal40, and additionally sealing (closing) the penetration holes18,19. It is good for the gasket92or the inside insulating member93to use a material superior to a chemical resistant property or a weather resistant property. The gasket92and the inside insulating member93may be configured with a resin material having an electrically insulating property and being able to be elastically deformed, for example, a fluorinated resin, such as perfluoroalkoxy fluorine resin (PFA), a polyphenylene sulfide resin (PPS), an aliphatic polyamide, or the like. The gasket92and the inside insulating member93may be, for example, integrated by insertion molding.

The electrode body20is, for example, a power generating element of the electric storage device1that includes the positive electrode22and the negative electrode24.FIG.4is a schematic view of the electrode body20in accordance with one embodiment. As shown inFIG.4, the electrode body20is a wound electrode body in which the positive electrode22formed in a long sheet shape and the negative electrode24formed in a long sheet shape are wound in a sheet longitudinal direction LD via the separator23. The electrode body20can be manufactured, for example, by winding the positive electrode22, the negative electrode24, and the separator23to be a cylindrical body and then to perform press molding on the cylindrical body. Thus, the electrode body20is formed in a flat shape, and has a pair of wide width surfaces20a(seeFIG.2andFIG.3). A number of the electrode bodies20arranged inside one exterior package12, which is not particularly restricted, may be equal to or more than two (plural), or may be one. As shown inFIG.3, herein, two electrode bodies are arranged inside the outer package12.

As shown inFIG.2andFIG.3, the electrode body20is accommodated in the exterior package12to make the winding axis direction WD and a vertical direction (an up and down direction) of the electric storage device1be approximately parallel. In this embodiment, the winding axis WL of the electrode body20is approximately parallel to the first surface12a, the third surfaces12d,12e, and the sealing plate14, and is approximately perpendicular to the second surfaces12b,12c. In addition, the wide width surface20aof the electrode body20is opposed to the first surface12aand the sealing plate14. In addition, one of end surfaces of the electrode body20is opposed to the second surface12band the other one of the end surfaces is opposed to the second surface12c. The end surface of the electrode body20is a laminate surface of the positive electrode22, the negative electrode24, and the separator23, and is a open surface. Incidentally, the electrode body20may be accommodated inside the case10under a state of being covered by an electrode body holder, which is not shown in figures and is configured with a resin sheet having an insulating property.

As shown inFIG.4, the positive electrode22includes a positive electrode collecting foil22c(for example, an aluminum foil) formed in a long strip-like shape and a positive electrode active material layer22afixed on at least one surface of the positive electrode collecting foil22c. Although not particularly restricting, one of side edge parts of the positive electrode22in the winding axis direction WD may be, as needed, provided with a protective layer22p. Incidentally, as a configuration material of the positive electrode active material layer22aand a configuration material of the protective layer22p, it is possible without particular restriction to use those utilized for this kind of electric storage device (a lithium ion secondary battery in this embodiment).

One of end parts (a top end part ofFIG.4) of the positive electrode collecting foil22cin the winding axis direction WD is provided with plural positive electrode tabs22t. The plural positive electrode tabs22tprotrude toward said one of end parts (the top end part ofFIG.4) in the winding axis direction WD. The plural positive electrode tabs22tare provided along the longitudinal direction LD of the positive electrode22at the intervals (intermittently). The positive electrode tab22tis a part of the positive electrode collecting foil22cand is a portion of the positive electrode collecting foil22cwhere the positive electrode active material layer22ais not formed (an active material layer unformed part). In the embodiment shown byFIG.4, a protective layer22pis provided at a base end side of the positive electrode tab22t. In this embodiment, plural positive electrode tabs22tprotrude in the winding axis direction WD more than the separator23. A shape and a size of the positive electrode tab22tcan be suitably adjusted, for example, in consideration of a state where it is connected to the positive electrode terminal30, based on a formed position of it, or the like. Plural positive electrode tabs22tare laminated at one of the end parts (the top end part ofFIG.4) in the winding axis direction WD, so as to configure a positive electrode tab group. Thus, a height (a length in the winding axis direction WD) of each positive electrode tab22tand a width (a length in the longitudinal direction LD) of each positive electrode tab22tmay not be the same. The positive electrode tab22tis an example of the “tab” disclosed herein.

As shown inFIG.4, the negative electrode24includes a negative electrode collecting foil24c(for example, a copper foil) formed in a long strip-like shape, and a negative electrode active material layer24afixed on at least one surface of the negative electrode collecting foil24c. Incidentally, as a configuration material of the negative electrode active material layer24a, it is possible without particular restriction to use one utilized for this kind of electric storage device (the lithium ion secondary battery in this embodiment).

At one of the end parts (the top end part ofFIG.4) of the negative electrode collecting foil24cin the winding axis direction WD, plural negative electrode tabs24tare provided. The plural negative electrode tabs24tprotrude to one of the end parts (the top end part ofFIG.4) in the winding axis direction WD. The plural negative electrode tabs24tare provided along the longitudinal direction LD of the negative electrode24at the intervals (intermittently). The negative electrode tab24tis a part of the negative electrode collecting foil24c, and is a portion of the negative electrode collecting foil24cwhere the negative electrode active material layer24ais not formed (an active material layer unformed part). In this embodiment, the plural negative electrode tabs24tprotrude in the winding axis direction WD more than the separator23. A shape and a size of the negative electrode tab24tcan be suitably adjusted, for example, in consideration of a state where it is connected to the negative electrode terminal40, based on a formed position of it, or the like. For example, the plural negative electrode tabs24tare laminated at one of the end parts (the top end part ofFIG.4) in the winding axis direction WD, so as to configure a negative electrode tab group. Thus, a height (a length in the winding axis direction WD) of each negative electrode tab24tand a width (a length in the longitudinal direction LD) of each negative electrode tab24tmay not be the same. The positive electrode tab22tis an example of the herein disclosed “tab”.

The separator23is a member establishing an insulation between the positive electrode active material layer22aof the positive electrode22and the negative electrode active material layer24aof the negative electrode24. The separator23in this embodiment configures an outer surface of the electrode body20. As the separator23, it is possible to use, for example, a porous sheet made of resin consisting of polyolefin resin, such as polyethylene (PE) and polypropylene (PP).

As shown inFIG.4, regarding the electrode body20, a lower end P3of the separator23is positioned at the lowest side, then a lower end P2of the negative electrode24is positioned, and a lower end P1of the positive electrode22is positioned at the uppermost side. Regarding widths of respective sheets (a length in the winding axis direction WD ofFIG.4, however, excluding the positive electrode tab22tand the negative electrode tab24t), they are larger in an order of the separator23, the negative electrode24, and the positive electrode22.

In the herein disclosed electric storage device1, the electrode body20includes the wide width surface20aopposed to the sealing plate14and the first surface12a. Further, it is arranged inside the case10to make the positive electrode tab22tand the negative electrode tab24tbe opposed to the second surface12bon which the positive electrode terminal30and the negative electrode terminal40are attached. Then, the positive electrode tab22tis joined to the positive electrode terminal30(specifically, the shaft part30a) by a metal joint50. Similarly, the negative electrode tab24tis joined to the negative electrode terminal40(specifically, the shaft part40a) by the metal joint50. The metal joint50is, for example, a portion where a tab and a terminal (here, the positive electrode tab22tand positive electrode terminal30, and the negative electrode tab24tand negative electrode terminal40) are melted and solidified so as to be joined mutually.

The exterior package12used in the herein disclosed electric storage device1includes an opening12hformed in a wide-width rectangular shape. Thus, not only the positive electrode tab22tand the positive electrode terminal30, but also the negative electrode tab24tand the negative electrode terminal40can be electrically connected, without the electrical collector body, by the metal joint50. In other words, the electrode body20and the positive electrode terminal30, and it and the negative electrode terminal40are directly and electrically connected. Accordingly, it is possible to suppress an increase in the electric resistance of the electric storage device1. The metal joint50can be, for example, suitably formed by laser welding, ultrasonic joining, resistance welding, or the like.

The exterior package12includes the opening12hformed in the wide-width rectangular shape, ant thus it is possible to easily accommodate the electrode body20inside the exterior package12. Accordingly, in comparison to the electric storage device in which the conventional case is used (see Patent Document 1), it is possible to make a clearance, required for accommodating the electrode body20, be smaller. By doing this, it is possible to further make a volume of the electrode body20be larger. In addition, by increasing the volume of the electrode body20, a movable range of the electrode body20in the case10is reduced. By doing this, it is possible to suitably reduce breakage risks of the positive electrode tab22tand the negative electrode tab24t. Accordingly, it is possible to compatibly implement an enhancement of the capacity (a high-volume energy density) and a conduction reliability of the electric storage device1.

In some preferable aspects, as shown inFIG.3, plural electrode bodies20are arranged inside the case10(the exterior package12), and the metal joint50is formed by joining the positive electrode tabs22tand the negative electrode tabs24tof plural electrode bodies20, and the positive electrode terminal30and the negative electrode terminal40. According to a configuration described above, it is possible to implement providing the electric storage device1whose capacity is further suitably enhanced. Incidentally, the electric storage device1of the present embodiment includes two electrode bodies20, to which the herein present disclosure is not restricted, and may include three or more electrode bodies20.

In some preferable aspects, inside the case10, the sealing plate14and a surface opposed to the sealing plate14within the wide-width surface20aof the electrode body20(the wide width surface20aof the electrode body20opposed to the sealing plate14, when plural electrode bodies20are accommodated in the case10) are abutted. In other words, it is configured to make the wide width surface20aof the electrode body20be pushed by the sealing plate14, when the electrode body20is accommodated and the sealing plate14and the exterior package12are welded. According to the configuration described above, a movement of the electrode body20inside the case10is regulated even in a situation where a vibration, an impact, or the like are applied at the time when the electric storage device1is used. By doing this, it is possible to further suitably reduce the damage risks of the positive electrode tab22tand the negative electrode tab24t. Accordingly, it is possible to provide the electric storage device1whose conduction reliability is further enhanced. Incidentally, when the electric storage device1is formed in the aspect described above, it is preferable that, for example, among the wide width surface20aof the electrode body20, approximately 70% or more is abutted on the sealing plate14, or approximately 80% or more is abutted on the sealing plate14.

<Manufacturing Method of Electric Storage Device1>

The electric storage device1can be manufactured by preparing the case10as described above (the exterior package12and the sealing plate14), the electrode body20(one or plural, herein two), the electrolytic solution, the positive electrode terminal30, and the negative electrode terminal40, and by using a manufacturing method, for example, which includes a terminal assembling step, an electrode body accommodating step, a metal joint forming step, a sealing-plate sealing step, and a liquid injection step, typically in this order. The manufacturing method of the electric storage device1is characterized by using the case10and the electrode body20which are as described above, and then by performing the electrode body accommodating step, the metal joint forming step, and the sealing step. The other manufacture processes may be similar to conventional manufacture processes. In addition, the herein disclosed manufacturing method may further include a different step at an arbitrary stage.

At the terminal assembling step, the positive electrode terminal30, the negative electrode terminal40, the gasket92, and the inside insulating member93are assembled on the second surface12bof the exterior package12. The negative electrode terminal40can be fixed on the second surface12bof the exterior package12, for example, by a caulking process (riveting). The caulking process is performed, while the gasket92is sandwiched between the negative electrode terminal40and the second surface12bof the exterior package12and further the insulating member80is sandwiched between the second surface12bof the exterior package12and the shaft part40aof the negative electrode terminal40(seeFIG.8). By doing this, an end part of the shaft part40aof the negative electrode terminal40is caulked. By the caulking process as described above, the gasket92and the inside insulating member93are compressed, the negative electrode terminal40, the second surface12bof the exterior package12, and the inside insulating member93are integrally fixed on the second surface12bof the exterior package12, and additionally the penetration hole19is sealed. Incidentally, an assembling method for the positive electrode terminal30side may be similar to the assembling method for the negative electrode terminal40side described above. In addition, the terminal assembling step is not restricted to this, and thus, for example, the second surface12bof the exterior package12, the positive electrode terminal30, and the negative electrode terminal40, and the gasket92and the inside insulating member93may be integrated by an insertion molding.

At the electrode body accommodating step, the electrode body20is accommodated in the exterior package12.FIG.5is a schematic view that is to explain the electrode body accommodating step and the tab joining step in accordance with one embodiment. InFIG.5, a join planned part50a(a formation planned part of the metal joint50) is represented by an imaginary line. At that time, the electrode body20is arranged to make one of the wide width surfaces20aof the electrode body20be opposed to the first surface12aand to make the positive electrode tab22tand the negative electrode tab24tbe opposed to the second surface12bto which the positive electrode terminal30and the negative electrode terminal40are attached. Here, the positive electrode tab22tis bent and is arranged to be opposed to the shaft part30aof the positive electrode terminal30. Similarly, the negative electrode tab24tis bent and is arranged to be opposed to the shaft part40aof the negative electrode terminal40. Incidentally, in a situation where the electric storage device1including plural electrode bodies20is manufactured, it is possible to perform the electrode body accommodating step divided by plural times, while sandwiching the tab joining step. In the present embodiment, as shown inFIG.5, the electrode body accommodating step is firstly performed for one electrode body20among two electrode bodies20. Then, after the tab joining step, the electrode body accommodating step is performed for the remaining one of the electrode bodies20.

At the tab joining step, the plural positive electrode tabs22tand the positive electrode terminal30, and the plural negative electrode tabs24tand the negative electrode terminal40are electrically joined. Here, a joining method by laser welding is explained as an example, but the herein present disclosure is not restricted to this, and thus, for example, the above described joining method may be used. At first, as shown inFIG.5, arrangement is performed to make the negative electrode tab24tof the electrode body20be stacked on the shaft part40aof the negative electrode terminal40. At that time, the negative electrode tab24tmay be folded and bent in order to make the shaft part40aof the negative electrode terminal40be easily stacked. In a situation where the electric storage device1includes the plural electrode bodies20, as shown inFIG.3andFIG.5, the negative electrode tab24tof the other electrode body20may be further stacked on the negative electrode tab24tof one electrode body20. Then, in a state where the negative electrode tab24tis stacked on the shaft part40aof the negative electrode terminal40, a laser is used to scan on the join planned part50a. By doing this, the metal joint50is formed, and the negative electrode terminal40and the negative electrode tab24tare electrically connected. Incidentally, a joining method for the positive electrode tab22tand the positive electrode terminal30may be similar to the above described joining method for the negative electrode tab24tand the negative electrode terminal40. Additionally, inFIG.5, the third surface12eof the exterior package12is positioned at the lower side for convenience sake of explanation, but the herein present disclosure is not restricted to this. At the tab joining step, based on the joining method or a jig used for joining, it is possible to perform the tab joining step in a state where the exterior package12is tilted by an angle at which it is easy to form the metal joint50.

At the sealing-plate sealing step, the opening12hof the exterior package12and the sealing plate14are used for sealing.FIG.6is a schematic view that is to explain the sealing-plate sealing step in accordance with one practical example. InFIG.6, for convenience sake of explanation, a press direction of the sealing plate14is represented by a white arrow and a scanning path of a laser L is represented by an imaginary line. As shown inFIG.6, the sealing plate14, in which to the opening12hof the exterior package12the sealing plate14is fit, is pushed into a first surface12adirection (a white arrow direction ofFIG.6) of the exterior package12. Then, while a state is held that the sealing plate14is pushed into the first surface12adirection of the exterior package12, the sealing plate14and the exterior package12are sealed. Thus, in a state where the wide width surface20aopposed to the sealing plate14of the electrode body20at the closest position to the sealing plate14is abutted, the opening12hof the exterior package12is sealed with the sealing plate14. Accordingly, it is possible to further suitably reduce damage risks of the positive electrode tab22tand the negative electrode tab24t. Here, along a circumferential edge of the sealing plate14(in the imaginary line direction ofFIG.6), the laser L is allowed to scan. However, the sealing method is not restricted to this.

At the sealing-plate sealing step, a press strength of the sealing plate14is not particularly restricted, can be changed suitably based on a material, a thickness, or a size of the case10. For example, the press strength of the sealing plate14may be equal to or more than 10 kN.

At the liquid injection step, the electrolytic solution is injected to the inside of the case10from the liquid injection hole16. Then, the liquid injection hole16is covered by the sealing member16aso as to hermetically seal the case10. Thus, it is possible to manufacture the electric storage device1.

Although the electric storage device1can be used for various purposes, it can be suitably used for a purpose in which increasing a capacity of the electric storage device1is required, or a purpose in which an external force, such as vibration and impact, may be applied at the use time, typically as a power source (power supply for driving) for a motor mounted on various vehicles, for example, a passenger car, a truck, or the like. The kind of the vehicle is not particularly restricted, but it is possible to use it, for example, on a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), a battery electric vehicle (BEV), or the like.

Above, some embodiments in accordance with the herein present disclosure are explained, but the above described embodiments are merely examples. The herein present disclosure can be implemented in other several forms. The herein present disclosure can be executed based on the contents disclosed in the present specification, and the technical common sense in the present field. The technique recited in the appended claims includes variously deformed or changed versions of the embodiments that have been illustrated above. For example, one part of the above described embodiment can be replaced with another deformed aspect, and furthermore another deformed aspect can be added to the above described embodiment. In addition, unless a technical feature is explained to be essential, this technical feature can be appropriately deleted.

While described above, as a particular aspect of the herein present disclosure, it is possible to use each item described below.Item 1: An electric storage device, comprising:an electrode body in which a long sheet-shaped positive electrode and a long sheet-shaped negative electrode are wound in a sheet longitudinal direction via a separator and which comprises a pair of opposed wide width surfaces;a case which is formed in a hexahedron shape, which is configured to accommodate the electrode body, and which comprises:an exterior package comprising a first surface formed in a wide width rectangular shape, an opening opposed to the first surface, a pair of opposed second surfaces extending from an outer edge of the first surface to the opening, and a pair of opposed third surfaces extending from the outer edge of the first surface to the opening; anda sealing plate configured to seal the opening, opposed to the first surface, and formed in a wide width rectangular shape; and terminals electrically connected to the electrode body, whereineach of the positive electrode and the negative electrode comprises plural tabs protruding at one of end parts in a winding axis direction of the electrode body,penetration holes are provided on one of the second surfaces,the terminals are inserted into the penetration holes,the electrode body is arranged inside the case, wherein the wide width surfaces respectively face the sealing plate and the first surface, and the tabs face the second surfaces to which the terminals are attached, anda metal joint is provided to connect the terminals and the tabs.Item 2: The electric storage device recited in item 1, whereinplural electrode bodies are arranged inside the case, andthe metal joint is formed by joining the tabs of the plural electrode bodies and the terminals.Item 3: The electric storage device recited in item 1 or 2, whereinit is configured that the wide width surface of the electrode body is pushed by the sealing plate when the sealing plate and the exterior package are welded.