JP2009259450A - Battery and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a square battery having high reliability in which an electrode unit of a flat shape is housed in a case of a battery at a prescribed correct position, without its inclining. <P>SOLUTION: The square battery is provided with a square case 10, of which the periphery of an aperture 12 housing an electrode unit inside, is constructed of a pair of long-side sidewalls 14 and a pair of short-side sidewalls 16, the electrode unit having a shape corresponding to the shape of the square case 10, and a sealing plate, to cover the aperture 12. At the periphery of the aperture 12, the end parts 14a, 14c contacting respectively the short-side sidewalls 16 of the pair of long-side sidewalls 14, and at least any of the pair of end parts out of a pair of end parts which contact one of the short-side wide walls and are opposed to each other interposing the aperture 12 and the other pair of end parts 14a, 14c, which contact the other short-side sidewalls 16 and are opposed to each other interposing the aperture, are formed so as to be thicker than the center part 14b of the long-side sidewalls. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery including a rectangular case that accommodates an electrode body unit and a method for manufacturing the same. Specifically, the present invention relates to the shape of the square case.

  Various batteries, for example, lithium secondary batteries such as lithium ion batteries, chemical batteries such as nickel metal hydride secondary batteries, or physical batteries such as electric double layer capacitors, power sources mounted on vehicles, personal computers, It is used as a power source mounted on portable terminals and other electrical products. A typical form of such a battery is a battery of a type in which a predetermined electrode body unit and an electrolyte are sealed inside a case (housing) typically made of metal. Typically, in such a sealed battery, after an electrode body unit composed of a positive electrode and a negative electrode is housed in a metal case, the outside of the opening of the case (that is, the housing port for housing the electrode body unit) is removed. A sealing plate (lid member) is laser welded to the periphery to seal (seal) the case opening (see Patent Document 2).

The battery case used for this type of battery can have various shapes. For example, as a vehicle-mounted battery, a shape in which a large number of batteries are efficiently arranged in a limited space is preferable. As a typical example, a flat rectangular corner corresponding to the shape of the electrode body unit that accommodates a flat electrode body unit such as a wound electrode body or a laminated electrode body as described in Patent Document 1. A mold case (typically a rectangular parallelepiped square case) is exemplified. In addition, in Patent Document 2, for the purpose of improving rigidity, the thickness of a pair of short side portions (short side walls) is a pair of long side portions (long side walls) out of the periphery of the rectangular case opening. A square case thicker than the plate thickness is described. Patent Document 3 discloses a pair of long side portions (long sides) of a rectangular case opening peripheral edge for the purpose of improving the welding strength of a portion where stress can concentrate when the case internal pressure increases. In the side wall, a square case is described in which the central portion is thicker than both ends.
Japanese Patent Laid-Open No. 2002-8708 JP-A-11-135080 JP 2006-260883 A

  However, a flat electrode body unit such as a wound type or a laminated type has a positive electrode current collector foil and a negative electrode current collector foil formed of different types of metal foils, and is wound or stacked together with a separator. After that, it is formed into a flat shape. For this reason, current collector foil lamination at the positive electrode side end due to differences in elasticity or foil thickness due to the difference in the type of metal constituting the current collector foil of each positive and negative electrode (for example, aluminum foil as the positive electrode and copper foil as the negative electrode) The thickness of the portion and the thickness of the current collector foil laminated portion at the negative electrode side end portion tend to be different. Therefore, when the electrode body unit having such a configuration is inserted into the square case, the arrangement position (holding posture) of the electrode body unit is predetermined within the case due to the difference in the thickness of the current collector foil laminated portion. It is easy to deviate from.

  More specifically, with reference to the long side wall of the peripheral part constituting the rectangular opening of the rectangular case, the electrode unit is inserted into the case substantially parallel to the long side wall. It is desirable that the difference between the thicknesses of the positive and negative current collector foil laminated portions be “displacement” or “inclination” as viewed from the reference long side wall (long side) of the case opening when the electrode unit is inserted. May occur. In particular, in the wound electrode body unit, the curvature is likely to change at the folded portion (that is, the end of the positive / negative current collector foil laminated portion), and therefore the electrode body unit is likely to be inclined (displaced) inside the case.

  Such inclination (displacement) occurs when the positive electrode current collecting terminal and the negative electrode current collecting terminal for external connection provided in the electrode body unit are attached to the sealing plate (lid member). In conjunction with the inclination, the mounting position of the sealing plate at the case opening is also shifted from the predetermined position. The mounting position shift of the sealing plate at the case opening is relatively large in a part between the sealing plate (specifically, a fitting convex surface formed on the inner surface side of the sealing plate) and the periphery of the case opening. Cause formation. Such a large gap is preferable because it facilitates welding spatter (metal powder) from being scattered into the case through the large gap when the sealing plate is laser welded to the periphery of the case opening to seal the case opening. Absent.

  In addition, as one measure for preventing the occurrence of the gap as described above, it is possible to correct the arrangement position in the case of the electrode body unit itself with a suitable holding jig, If an attempt is made to correct the inclination of the electrode body unit in the case using such a correction means (jig), an excessive load is applied to the electrode body unit itself accommodated in the case, and the durability of the battery is impaired. Since there is a possibility, it is not preferable.

  Therefore, the present invention has been created to solve the conventional problems related to a battery including a flat electrode body unit that easily generates a large gap between the sealing plate and the periphery of the case opening as described above. The object is to provide a highly reliable prismatic battery in which a flat electrode body unit is accommodated in a predetermined correct position without tilting inside the case. Another object is to provide a battery manufacturing method capable of realizing this.

  In order to achieve the above object, the battery provided by the present invention includes a rectangular case in which the periphery of the opening for accommodating the electrode body unit is composed of a pair of long side walls and a pair of short side walls. The battery includes an electrode body unit having a shape corresponding to the shape of the square case, and a sealing plate for closing the opening.

  In the battery provided by the present invention, at the periphery of the opening, each of the pair of long side walls is in contact with the short side wall, i). A pair of end portions in contact with one short side wall and facing each other with the opening interposed therebetween; ii). At least one of the pair of end portions in contact with the other short side wall and facing each other across the opening is formed so as to be thicker than the central portion of the long side wall. It is characterized by being.

  In the present specification, the “battery” refers to a power storage device that can extract predetermined electrical energy, and is not limited to a specific power storage mechanism (configuration of an electrode body or an electrolyte). A lithium secondary battery, a nickel hydride secondary battery, other secondary batteries, or a capacitor such as an electric double layer capacitor (that is, a physical battery) is a typical example included in the battery herein.

  In the present specification, the “electrode body unit” refers to a structure constituting the main body of a battery including at least one positive electrode and one negative electrode.

  Further, in the present specification, the “case” is one member constituting the battery disclosed herein, and accommodates an electrode body unit and an electrolyte, and has an opening (that is, an electrode body unit accommodation opening). The case is referred to as a “square case”, and the opening has a rectangular shape.

  In the battery of the present invention having the above-described configuration, at the periphery of the opening, the pair of end portions opposed to each other with the opening on the short side wall side of at least one of the pair of long side walls are long side walls It is formed thicker than the central part. In the battery having such a configuration, when the electrode body unit having a predetermined shape is inserted into the rectangular case at the time of construction, the inner wall surface of the thick end and the corresponding end of the electrode body unit ( For example, in the above-described wound electrode body unit, the current collector foil laminated portion including the folded portion is in contact with each other (typically, the electrode body unit is sandwiched between a pair of inner wall surfaces). The electrode body unit is correctly accommodated in a predetermined position while being held in a correct posture. Therefore, there is no inclination of the electrode body unit as described above between the electrode body unit housed in a predetermined position and the case inner wall, and the sealing plate and the case opening due to the inclination of the electrode body unit as described above. A large gap between the peripheral edges does not occur.

  Therefore, in the battery disclosed here, spatter is prevented from being scattered in the gap inside the case during laser welding at the time of sealing, and as a result, it is possible to provide a high-quality and highly reliable battery. .

  In a preferred aspect of the battery provided by the present invention, at the periphery of the opening, the thick end is formed so that the thickness gradually increases as it approaches the short side wall in contact with the end. It is characterized by.

  In the battery having such a configuration, when the electrode body unit is inserted into the square case at the time of construction, the end portions of the positive and negative electrode current collector foil laminated portions of the electrode body unit are formed to have the thickness of the square case. It is pinched | interposed by the edge part (namely, edge part formed so that it became thick so that it was near a short side wall). As a result, the electrode body unit is accommodated while maintaining a predetermined arrangement position (holding posture) set in advance. In addition, since the central part of the long side wall is thinner than the thick end, the electrode unit is excessively pressed by the central part of the long side wall when the electrode unit is inserted into the case. Not. As a result, the electrode body unit is smoothly inserted into the case through the case opening. Therefore, it is possible to provide a battery with excellent productivity.

  In another preferred embodiment of the battery provided by the present invention, at the periphery of the opening, both ends of the pair of long side walls contacting the short side wall are formed with the thickness. It is characterized by being.

  In the battery having such a configuration, since both ends of the pair of long side walls are formed thick, the electrode body unit is more stably inserted and held at a predetermined position in the case when the battery is constructed. Is done. As a result, provision of a battery with high reliability in the long term is realized.

  In another preferred embodiment of the battery provided by the present invention, the electrode body unit is housed in the case in a state of being in contact with the inner wall surfaces of the pair of thick ends. To do.

  In the battery having such a configuration, the electrode body unit is accommodated in contact with the inner wall surfaces of the thick end portions of the pair of long side walls when the battery is constructed. For this reason, there is no inclination (displacement) of the electrode body unit between the electrode body unit accommodated in the predetermined position and the inner wall of the case. Thereby, a big clearance gap does not arise between the sealing board connected via this positive electrode current collection terminal and negative electrode current collection terminal for external connection, and a case opening part periphery. For this reason, for example, when a sealing plate is laser welded to the periphery of the case opening to seal the case opening, welding spatter is less likely to be scattered inside the case. As a result, it is possible to prevent a failure such as an internal short circuit and provide a highly reliable battery.

  The present invention also provides a battery manufacturing method. That is, the battery manufacturing method provided by the present invention includes a rectangular case in which the periphery of the opening for accommodating the electrode body unit is composed of a pair of long side walls and a pair of short side walls, It is a method of manufacturing a battery including an electrode body unit having a shape corresponding to the shape of a square case and a sealing plate for closing the opening.

  In the manufacturing method according to the present invention, as the rectangular case, at the peripheral edge of the opening, an end portion in contact with the short side wall of each of the pair of long side walls, i). A pair of end portions in contact with one short side wall and facing each other across the opening; ii). Of the other pair of end portions that are in contact with the other short side wall and are opposed to each other with the opening therebetween, at least one of the pair of end portions is formed to be thicker than the central portion of the long side wall. Prepare a square case. And when accommodating the said electrode body unit in the said case, hold | maintain this electrode body unit in the said case, hold | maintaining the corresponding edge part of this electrode body unit between each inner wall surface of said thick pair of edge part. It is characterized by inserting.

  In the manufacturing method of this aspect, the pair of end portions opposed to each other with the opening on at least one short side wall side of the pair of long side walls of the square case sandwiched from the central portion of the long side wall. It is formed thick. Therefore, when the electrode body unit having a predetermined shape is inserted into the square case, the inner wall surface of the thick end and the corresponding end of the electrode body unit (for example, the above-described wound electrode body) The unit is in a state of being in contact with each other (typically a state in which the electrode body unit is sandwiched between a pair of inner wall surfaces) and the electrode body unit is held in a correct posture. It can be correctly stored in a predetermined position. Therefore, the inclination of the electrode body unit as described above does not occur between the electrode body unit housed in a predetermined position and the inner wall of the case, and the sealing plate and the peripheral edge of the case opening due to the inclination of the electrode body unit are not generated. There is no large gap between them.

  Therefore, according to the manufacturing method disclosed here, it is possible to prevent spatter from being scattered in the gap inside the case during laser welding at the time of sealing. As a result, a battery with high quality and high reliability can be suitably manufactured.

  In another aspect preferable as a method for manufacturing a battery according to the present invention, at the periphery of the opening, the thick end portion gradually increases as it approaches the short side wall in contact with the end portion. It is formed.

  In the manufacturing method according to this aspect, when the electrode body unit is inserted into the square case by using the square case formed such that the wall thickness of the long side wall gradually increases as it approaches the short side wall, The ends of the positive and negative current collecting foil laminated portions of the unit are sandwiched by the end portions formed so as to be thicker toward the short side wall of the square case. As a result, the electrode body unit can be accommodated while maintaining a predetermined arrangement position (holding posture) determined in advance. Also, since the central part of the long side wall is thinner than the thick end, the central part of the long side wall excessively presses the electrode unit when inserting the electrode unit into the case. do not do. As a result, the electrode body unit can be smoothly inserted through the case opening. Therefore, a battery having excellent productivity can be suitably manufactured.

  Moreover, in another preferable aspect as a battery manufacturing method according to the present invention, at the peripheral edge of the opening, both end portions in contact with the short side walls of the pair of long side walls are formed thick. It is characterized by.

  In such a manufacturing method, since the end portions in contact with the short side walls of each of the pair of long side walls are formed thick, the electrode body unit is further placed at a predetermined position in the case when the battery is constructed. It can be stably inserted and held. As a result, a battery with high reliability in the long term can be suitably manufactured.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals are given to members / parts having the same action.

  The battery of the present invention (typically a square battery) is a battery characterized by the shape of the battery case (specifically, the thickness and shape of the side wall at the periphery of the case opening). Technical matters other than those specifically mentioned in the manual and necessary for the implementation of the present invention (for example, means for welding the sealing plate and the case, construction of the electrode unit and electrolyte, etc. for battery construction) These various processes) can be understood as a design matter of those skilled in the art based on the prior art. The present invention can be implemented based on the technical contents disclosed in the present specification and the common general technical knowledge in the field.

  A prismatic battery 100 according to an embodiment will be described in detail with reference to FIGS.

  FIG. 1 is a perspective view schematically showing a prismatic battery 100 according to an embodiment. FIG. 2 is a plan view of the prismatic battery 100 according to one embodiment. 3 is a sectional view taken along line III-III in FIG. 1, and FIG. 4 is a sectional view taken along line IV-IV in FIG. Furthermore, FIG. 5 is a plan view of the square case 10 according to the embodiment.

  The square battery 100 according to this embodiment includes an electrode body unit 20 in which a positive electrode sheet 22 and a negative electrode sheet 27 are wound together with a separator 25, a square case 10 that houses the electrode body unit 20, and a sealing plate 30. It is a battery provided.

  As shown in FIG. 1, the external shape of the rectangular battery 100 according to the present embodiment includes a rectangular parallelepiped case 10 and a sealing plate 30 that closes an opening 12 (see FIG. 5) of the rectangular case 10. Composed. The rectangular case 10 includes a pair of long side walls 14, a pair of short side walls 16, and a bottom wall 18 (see FIGS. 3 and 4), and is opposed to the bottom wall 18 (that is, an opening). 12) is closed by the sealing plate 30.

  Next, the shape of the sealing plate 30 of the square battery 100 according to the present embodiment will be described with reference to FIG.

  Although the shape of the sealing plate 30 is not particularly limited, as shown in FIG. 2, the sealing plate 30 of the rectangular battery 100 according to the present embodiment has the same shape as the bottom wall 18 of the rectangular case 10, and The mold case 10 is attached to the opening 12. The sealing plate 30 is provided with a positive current collecting terminal 24 and a negative current collecting terminal 29 for external connection, and a part of the positive current collecting terminal 24 and the negative current collecting terminal 29 is provided on the sealing plate 20. It protrudes to the surface side. Further, a convex portion 31 (see FIG. 4) is formed on the back side surface of the sealing plate 30, and the opening portion 12 of the square case 10 is inserted into the case opening portion 12 (that is, fitted). It is attached to.

  As shown in FIGS. 3 and 4, the rectangular battery 100 according to the present embodiment accommodates a flat electrode body unit 20. The electrode unit 20 includes a positive electrode sheet 22 having a positive electrode active material layer on the surface of a long sheet-like positive electrode current collector 23 and a negative electrode having a negative electrode active material layer on the surface of a long sheet-like negative electrode current collector 28. A sheet 27 and a long sheet-like separator 25, and the positive electrode sheet 22 and the negative electrode sheet 27 are wound together with the two separators 25 and wound, and the obtained wound body is crushed from the side direction and ablated. Is formed into a flat shape.

  In the wound positive electrode sheet 22, the positive electrode current collector 23 is exposed without being provided with the positive electrode active material layer at one end portion 20a along the longitudinal direction, while the negative electrode sheet is wound. 27, one end 20c along the longitudinal direction is not provided with the negative electrode active material layer, and the negative electrode current collector 28 is exposed. Specifically, as shown in the drawing, the exposed positive electrode current collector 23 (that is, the end portion 20a) is laminated on one end in the longitudinal direction (that is, the winding axis direction) of the electrode body unit 20, and the other end. Has a structure in which the exposed negative electrode current collector 28 (that is, the end 20c) is laminated.

  Further, the cathode current collector terminal 24 was joined to the exposed portion 20a of the cathode current collector 23, and the anode current collector terminal 29 was joined to the exposed portion 20c of the anode current collector 28 to form the flat shape. The positive electrode sheet 22 or the negative electrode sheet 27 is electrically connected. As a joining method, for example, various welding methods such as an ultrasonic welding method and a resistance welding method can be used.

  The material and the member constituting the electrode body unit 20 may be the same as those of the electrode body unit provided in the conventional battery, and are not particularly limited. As a typical example of an electrode body unit to which the technology disclosed herein is preferably applied, the structure of the battery of the present invention will be described in detail below mainly using a lithium ion battery as an example, but the present invention will be described in the embodiment according to the present invention. It is not intended to be limited to what has been done.

  As the positive electrode current collector 23 constituting the positive electrode sheet 22, a sheet material made of a metal having good conductivity can be used. For example, a conductive member made of aluminum or an alloy mainly composed of aluminum can be given. Moreover, as an electrode active material which is a main component of the positive electrode active material layer, one or more kinds of materials conventionally used in lithium ion batteries can be used without particular limitation. For example, an oxide-based positive electrode active material having a layered structure, an oxide-based positive electrode active material having a spinel structure, and the like used for a general lithium ion battery can be preferably used.

  On the other hand, as the negative electrode current collector 28 constituting the negative electrode sheet 27, for example, a sheet material (preferably copper foil) made of a metal such as copper can be used. Moreover, as an electrode active material which is a main component of the negative electrode active material layer, one or more kinds of materials conventionally used in lithium ion batteries can be used without particular limitation. For example, a particulate carbon material (carbon particles) including a graphite structure (layered structure) can be given.

  The positive electrode sheet 22 and the negative electrode sheet 27 can be preferably produced by applying a composition in which the above electrode active material is dispersed in an appropriate solvent to each of the current collectors 23 and 28 and drying the composition. In addition, a conductive material, a binder, a thickener, etc. can be added to the said composition as needed.

  As a suitable sheet-like separator 25 used by being overlapped between the positive electrode sheet 22 and the negative electrode sheet 27 produced as described above, one made of a porous polyolefin-based resin can be cited. When a solid electrolyte or a gel electrolyte is used as the electrolyte, there may be a case where a separator is unnecessary (that is, in this case, the electrolyte itself can function as a separator).

  As a constituent material of the positive electrode current collector terminal 24, a metal material (preferably aluminum) of the same type as that of the positive electrode current collector 23 bonded to the current collector terminal 24 can be preferably used. On the other hand, as the constituent material of the negative electrode current collector terminal 29, the same metal material (preferably copper) as that of the negative electrode current collector 28 bonded to the current collector terminal 29 can be preferably used.

  Next, the shape of the square case 10, which is an embodiment that suitably implements the present invention, will be described. FIG. 5 is a plan view of the rectangular case 10 according to an embodiment of the present invention, that is, a view showing the shape of the opening 12 and the periphery of the rectangular case 10.

  The rectangular case 10 is a rectangular parallelepiped rectangular case 10 composed of a pair of long side walls 14, a pair of short side walls 16 and a bottom wall 18, and one surface (surface facing the bottom wall 18). The peripheral edge constitutes a rectangular opening 12 having the pair of long sides (the top surface of the long side wall 14) and a pair of short sides (the top surface of the short side wall 16). A predetermined electrode body unit 20 and an electrolytic solution can be accommodated in the case 10 through the opening 12.

  The material of the square case 10 is not particularly limited, but a metal square case 10 is suitable. For example, a case 10 made of an iron material such as stainless steel or nickel-plated steel, aluminum, or an alloy thereof may be used. Aluminum is preferable.

  As shown in FIG. 5, the peripheral edge of the opening 12 of the rectangular case 10 according to the present embodiment is in contact with the short side walls 16 of the pair of long side walls 14 and is opposed to each other with the opening 12 interposed therebetween. The pair of end portions 14a and 14c are formed to be thicker than the central portion 14b of the long side wall. Although not particularly limited as long as the object of the present invention can be achieved, for example, the length of the long side wall 14 is 50 to 200 mm, the length of the short side wall 16 is 5 to 30 mm, and the case thickness is 0.00. In the case of a 3 to 2 mm square case, the thickness of the end portions 14a and 14c of the long side wall is suitably about 0.3 to 1 mm, and the thickness of the long side wall central portion 14b is about 0.5 to 2 mm. Is preferred.

  In this manner, the pair of end portions 14a and 14c opposed to each other with the opening 12 on the short side wall side 16 of the pair of long side wall end portions 14a and 14c sandwiched therebetween is formed into a square shape. When the battery unit 100 is constructed, when the electrode body unit 20 is inserted into the square case 10, the current collectors of the inner wall surfaces of the end portions 14 a and 14 c formed to be thick and the corresponding end portions of the electrode body unit 20 are used. Are in contact with each other and the electrode body unit 20 is sandwiched between them. As a result, the electrode body unit 20 can be correctly accommodated in a predetermined position while being held in a correct posture.

After housing the electrode body unit 20 as described above, the sealing plate 30 is attached to close the opening 12 of the square case 10. The sealing plate 30 according to the present embodiment is attached to the opening 12 of the square case 10 so that the convex portion 31 on the back side surface of the sealing plate 30 fits inward of the case opening 12. The periphery is sealed by welding. The welding technique itself may be the same as that used when welding a conventional battery case and a sealing plate (for example, laser welding using a YAG laser, a CO ₂ laser, or the like as a heat source), and is not particularly limited. The material of the sealing plate 30 may be a material different from that of the rectangular case 10, but is preferably a metal (for example, made of aluminum) that is the same material as the rectangular case 10.

  Further, the positive electrode current collector terminal 24 and the negative electrode current collector terminal 29 provided on the surface side of the sealing plate 30 are respectively connected to the positive electrode current collector 24 and the negative electrode current collector 29 of the electrode body unit 20 housed in the case 10. They are electrically connected (see FIG. 3). As a result of the structure in which the electrode body unit 20 and the sealing plate 30 are connected, for example, when the electrode body unit 20 is tilted from a predetermined position and accommodated in the case 10, the sealing plate is caused by the inclination of the electrode body unit 20. 30 also tilts, and a large gap is formed between the sealing plate 30 and the periphery of the case opening 12 (specifically, between the sealing plate 30 and the end 14a or 14c of the long side wall formed thick). Will occur. When there is a large gap between the sealing plate 30 and the periphery of the opening 12 of the case 10, when welding the periphery of the opening 12, spatter (metal pieces) is easily scattered from the gap into the case. As a result, an internal short circuit may occur.

  However, the prismatic battery 100 using the square case 10 according to the embodiment of the present invention has an electrode body unit as described above between the electrode body unit 20 housed in a predetermined position and the inner wall of the case 10. No inclination (displacement) of 20 occurs, and no large gap occurs between the sealing plate 30 and the case opening 12 due to the inclination of the electrode body unit 20.

  Therefore, in the square battery 100 according to the present invention, the electrode body unit 20 is accommodated in the square case 10, the sealing plate 30 is laser welded to the periphery of the opening 12 of the case 10, and the case opening 12 is sealed. When sealing (sealing), it is possible to prevent spatter (metal pieces) from being scattered in the gap inside the case during laser welding at the time of sealing, and as a result, the cause of an internal short circuit can be eliminated.

  In addition, the square case 10 according to the present embodiment is formed such that both ends of the end portions 14a and 14c of the long side wall are thick, but only one of the end portions (14a or 14c) is thick. By doing so, the object according to the present invention can be achieved. However, it is particularly preferable that both end portions are formed thick because the electrode body unit 20 can be stably inserted and held at a predetermined position in the case.

  Further, as shown in FIG. 5, the thick end portions 14a and 14c of the pair of long side walls 14 are formed so that the thickness gradually increases toward the short side wall 16 in contact with the end portions. ing.

  Thus, the case 10 formed so that the wall thickness gradually increases toward the short side wall 16 at the periphery of the case opening 12 is formed to have a gradually increased wall thickness when the electrode body unit 20 is inserted. The end portions 20a and 20c of the electrode body unit 20 can be easily sandwiched by the portions 14a and 14c, and the electrode body unit 20 can be smoothly and correctly accommodated in a predetermined position while being held in a correct posture. Further, since the central portion 14b of the case long side wall is formed thinner than the thick end portions 14a and 14c, the electrode body unit 20 is not pressed by the inner wall of the case 10, and the opening portion 12 is formed. Thus, the electrode body unit 20 can be inserted smoothly.

  Furthermore, the rectangular case 10 according to the present embodiment is such that the electrode body unit 20 is in contact with the inner wall surfaces of the thick end portions 14a and 14c of the pair of long side walls 14 at the periphery of the case opening 12. Housed inside the case. For this reason, there is no inclination (displacement) of the electrode body unit 20 between the electrode body unit 20 accommodated in a predetermined position and the inner wall of the case. As a result, a large gap does not occur between the sealing plate 30 and the case opening 12 that are connected to the electrode body unit 20 via the positive current collecting terminal 24 and the negative current collecting terminal 29 for external connection. Therefore, as described above, when the sealing plate 30 is laser-welded to the periphery of the case opening 12 and sealed, welding spatter is less likely to be scattered inside the case.

  Next, an embodiment in which the prismatic battery 100 (lithium secondary battery) is constructed using the prismatic case 10 provided by the present invention will be described. However, the present invention is not intended to be limited to those shown in the specific examples.

  First, the square case 10 shown in FIG. 5 according to the present invention is prepared. Next, the central portion 14b of the long side wall 14 of the case 10 is bent outward to open the opening 12 of the case 10, and between the inner wall surfaces of the pair of thick end portions 14a and 14c of the long side wall 14. The electrode body unit 20 is inserted while holding the corresponding ends 20a, 20c of the electrode body unit 20. At this time, the corresponding end portions 20a, 20c of the electrode body unit 20 are sandwiched between the inner wall surfaces of the end portions 14a, 14c of the pair of long side walls, so that the electrodes are placed at predetermined positions in the case 10. The body unit 20 can be accommodated without tilting. Thereby, the big clearance gap between the sealing board 30 and the periphery of the case opening part 12 resulting from the inclination of the electrode body unit 20 as mentioned above does not arise. Therefore, it is possible to prevent the spatter from scattering into the gap inside the case by laser welding at the time of sealing.

After the electrode body unit 20 is accommodated in the square case 10, an appropriate amount of a lithium salt (supporting salt) such as LiPF ₆ is dissolved in an electrolyte solution (a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC)) ) Is injected into the case 10. Then, the case opening 12 and the corresponding sealing plate 30 are attached, and the case opening 12 is sealed (sealed) by laser welding to complete the construction (assembly) of the prismatic battery 100.

  In addition, as said electrolyte solution for lithium ion batteries, the nonaqueous electrolyte solution containing the non-aqueous solvent and the lithium salt (supporting salt) which is added and melt | dissolved in this solvent can be used.

  The non-aqueous solvent is selected from non-aqueous solvents that are generally known to be usable for an electrolyte of a lithium ion battery, such as propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), and the like. One kind or two or more kinds can be used.

As the supporting salt to be contained in the electrolytic solution, one or two or more lithium compounds (lithium salts) selected from LiPF ₆ , LiBF ₄ , LiClO ₄ , and the like can be used.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The invention disclosed herein includes various modifications and alterations of the above specific examples. For example, in the above-described embodiment, the electrode body unit is accommodated such that the winding axis direction is along the long side wall (that is, the winding axis direction is horizontal). It can be accommodated such that the direction is orthogonal to the case bottom wall (that is, the winding axis direction is vertical).

  In addition, the battery to which the present invention can be applied is not limited to the above-described wound-type electrode body unit lithium ion battery, but is a stacked electrode body unit, or batteries having various contents with different electrode body constituent materials and electrolytes, For example, a lithium secondary battery other than a lithium ion battery having lithium metal or a lithium alloy as a negative electrode, a nickel metal hydride battery, a nickel cadmium battery, or an electric double layer capacitor may be used.

  Furthermore, in the rectangular case of the above-described embodiment, the end of the long side wall is formed so that the thickness gradually increases as it approaches the short side wall. You may form so that it may become thick gradually from the center part to a short side wall direction, or this edge part may be formed in fixed thickness.

1 is a perspective view schematically showing a rectangular battery 100 in which an electrode body unit 20 according to an embodiment is accommodated in a rectangular case 10. 1 is a plan view of a prismatic battery 100 in which an electrode body unit 20 according to an embodiment is accommodated in a prismatic case 10. FIG. It is the III-III sectional view taken on the line in FIG. It is the IV-IV sectional view taken on the line in FIG. It is a top view of the square case 10 which concerns on one Embodiment.

Explanation of symbols

10 Square Case 12 Opening 14 Long Side Side Wall 14a End of Long Side Side Wall (Positive Electrode Side)
14b Center part of long side wall 14c End of long side wall (negative electrode side)
16 Short side wall 18 Bottom wall 20 Electrode unit 20a End of electrode unit (positive electrode side)
20c End of electrode body unit (negative electrode side)
22 Positive electrode sheet 23 Positive electrode current collector 24 Positive electrode current collector terminal 25 Separator 27 Negative electrode sheet 28 Negative electrode current collector 29 Negative electrode current collector terminal 30 Sealing plate 31 Convex part 100 Square battery

Claims (7)

A rectangular case in which the periphery of the opening for accommodating the electrode body unit is composed of a pair of long side walls and a pair of short side walls;
An electrode body unit having a shape corresponding to the shape of the square case;
A sealing plate for closing the opening;
A battery comprising:
At the periphery of the opening, each of the pair of long side walls is in contact with the short side wall; i). A pair of end portions in contact with one short side wall and facing each other across the opening; ii). At least one of the pair of end portions in contact with the other short side wall and facing each other with the opening interposed therebetween is thicker than the center portion of the long side wall. A battery characterized by being formed.   2. The peripheral edge of the opening, wherein the thick end portion is formed so that the thickness gradually increases toward the short side wall in contact with the end portion. The battery described.   3. The battery according to claim 1, wherein at the peripheral edge of the opening, both ends of the pair of long side walls contacting the short side wall are formed with the thickness.   The battery according to claim 1, wherein the electrode body unit is accommodated in the case in a state of being in contact with inner wall surfaces of the pair of thick end portions. A rectangular case in which the periphery of the opening for accommodating the electrode body unit is composed of a pair of long side walls and a pair of short side walls, and an electrode body unit having a shape corresponding to the shape of the square case And a method of manufacturing a battery comprising a sealing plate that closes the opening,
As the square case, at the peripheral edge of the opening, each of the pair of long side walls is in contact with the short side wall, i). A pair of end portions in contact with one short side wall and facing each other across the opening; ii). Of the other pair of end portions that are in contact with the other short side wall and are opposed to each other with the opening therebetween, at least one of the pair of end portions is formed to be thicker than the central portion of the long side wall. Prepare a square case,
When the electrode body unit is housed in the case, the electrode body unit is inserted into the case while holding the corresponding end portion of the electrode body unit between the inner wall surfaces of the pair of thick ends. A method for producing a battery.   The manufacturing method according to claim 5, wherein the thick end portion is formed so as to gradually increase toward the short side wall in contact with the end portion at a peripheral edge of the opening. 7. The manufacturing method according to claim 5, wherein, at a peripheral edge of the opening, both ends of the pair of long side walls contacting the short side wall are formed with the thickness.

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