JP2011171079A - Battery cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of a current collecting tub when external forces such as vibrations or impacts are applied in a battery cell in which the current collecting tub extended from a plurality of electrodes is used. <P>SOLUTION: The battery cell includes: electrode group 2 that is wound squamously and in whorl; a plurality sheet of positive electrode current collecting tubs 6c that are extended from a plurality of portions in one end face of a positive collector 6a of a positive electrode 6;and a plurality of sheet of negative electrode current collecting tubs 7c that are extended from a plurality of portions in one end face of a negative collector 7a of a negative electrode 7, wherein the electrode group 2 has: bent sides 65 occupying both ends in a long side direction on the end face; and an unbent side 67 sandwiched by the bent sides 65, and the positive electrode current collecting tubs 6c are located at one of the bent side 65, the negative electrode current collecting tubs 7c are located at the other of the bent side 65 and moreover, both ends parallel to an extended direction of the positive electrode current collecting tubs 6c and the negative electrode tubs 7c. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a battery.

  In recent years, with the development of electronic devices, lithium secondary batteries have been developed as non-aqueous electrolyte secondary batteries that are small, lightweight, have high energy density, and can be repeatedly charged and discharged. Recently, non-aqueous electrolyte secondary batteries capable of rapid charging and high output discharge, suitable for in-vehicle secondary batteries mounted on hybrid vehicles and electric vehicles, and secondary batteries for power storage used for power leveling. Development of batteries is desired.

  In order to obtain excellent rapid charge performance and high output discharge performance in a nonaqueous electrolyte secondary battery, it is necessary to efficiently extract current. For this purpose, it is desirable to lead out current collecting tabs from a plurality of locations of the electrodes and to electrically connect these current collecting tabs to external terminals via leads.

  In Patent Document 1, a plurality of positive electrode current collecting tabs are fixed at intervals in the longitudinal direction of the positive electrode plate, and a plurality of negative electrode current collecting tabs are fixed at intervals in the longitudinal direction of the negative electrode plate. In a state where the plate and the negative electrode plate are wound, it is possible to obtain a high output by arranging the plurality of positive electrode current collecting tabs and the plurality of negative electrode current collecting tabs so as to face each other via separators. A lithium secondary battery is disclosed.

  In Patent Document 2, in a non-aqueous electrolyte secondary battery, the problem of heat generation and polarization can be reduced by providing at least one current collecting tab for extracting electricity for each of the positive electrode and the negative electrode for every 300 mm in length. It is disclosed.

  Patent Document 3 also discloses a battery in which tabs are derived from a plurality of positions of electrodes.

  However, as in Patent Documents 1 to 3, if the current collecting tab is led out from a plurality of positions of the electrode, there is a problem that a part of the current collecting tab is damaged when vibration or impact is applied to the battery from the outside.

JP-A-11-111340 JP 2006-260786 A JP 2001-85042 A

  An object of the present invention is to prevent damage to a current collecting tab when an external force such as vibration or impact is applied to a battery using the current collecting tab extended from a plurality of positions of an electrode.

  In the first embodiment of the present invention, a container, an electrode housed in the container, including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and wound in a flat spiral shape A plurality of positive electrode current collector tabs extending from a plurality of locations on one end surface of the positive electrode current collector of the group, and a plurality of positive electrode current collector tabs extending from a plurality of locations on one end surface of the negative electrode current collector of the negative electrode Further, a plurality of negative electrode current collecting tabs, a lid for closing the opening of the container, a positive electrode terminal provided on the lid and electrically connected to the positive electrode current collecting tab, provided on the lid, A negative electrode terminal electrically connected to the negative electrode current collector tab, the electrode group has a curved portion occupying both ends in the long side direction on the end surface, and a non-curved portion sandwiched between the curved portions, The positive electrode current collecting tab is located in one of the curved portions, and the negative electrode current collecting tab is There is provided a battery characterized in that both ends of the positive electrode current collecting tab and the negative electrode current collecting tab parallel to the extending direction of the positive electrode current collecting tab and the negative electrode current collecting tab are located in the non-curved part. .

2nd Embodiment of this invention WHEREIN: The distance between the said positive electrode current collection tabs in the said positive electrode and the distance between the said negative electrode current collection tabs in the said negative electrode are respectively represented by following (1) Formula, It is characterized by the above-mentioned. A battery is provided.
2nπd (1)
However, n is the position of the said positive electrode current collection tab counted from the inner peripheral side of the said electrode group, or the position of the said negative electrode current collection tab, d is the thickness of the said positive electrode, the thickness of the said negative electrode, and It is the sum of twice the thickness of the separator, and π is the circumference.

  ADVANTAGE OF THE INVENTION According to this invention, damage to the current collection tab when external force, such as a vibration and an impact, is applied to the battery using the current collection tab extended from the several places of an electrode can be prevented.

The disassembled perspective view about the principal part of the battery of 1st Embodiment. FIG. 2 is an exploded perspective view showing a manufacturing process of the battery of FIG. 1. The expanded view of the electrode group of the battery of 1st Embodiment. The upper surface schematic diagram which shows the curved part and non-curved part in the end surface of an electrode group. The upper surface schematic diagram of the electrode group of the battery in one aspect. The upper surface schematic diagram of the electrode group of the battery in another aspect. The upper surface schematic diagram of the electrode group of the battery in another aspect. The top view which shows the positive / negative electrode of the battery of 2nd Embodiment. The upper surface schematic diagram of the electrode group of the battery of the comparative example 1. FIG. The upper surface schematic diagram of the electrode group of the battery of the comparative example 2. FIG. The upper surface schematic diagram of the electrode group of the battery of the comparative example 3. FIG.

  Hereinafter, a battery according to an embodiment of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments.

(First embodiment)
A square nonaqueous electrolyte secondary battery will be described as an example as the first embodiment. FIG. 1 is an exploded perspective view of a sealed prismatic non-aqueous electrolyte secondary battery. This battery includes a container 1, an electrode group 2 housed in the container 1, a nonaqueous electrolyte solution (not shown) housed in the container 1, a lid 3 that closes the opening of the container 1, and a lid 3 A positive electrode terminal 50 and a negative electrode terminal 5.

  The container 1 has a bottomed rectangular tube shape, and is an outer can formed from, for example, a metal such as aluminum, an aluminum alloy, iron, or stainless steel.

  The electrode group 2 includes a positive electrode, a negative electrode, and a separator 59 disposed between the positive electrode and the negative electrode. The electrode group 2 is formed into a flat shape by winding the separator 59 between the positive electrode and the negative electrode in a spiral shape and then press-molding the whole.

  FIG. 3 shows a development view of the electrode group 2. The positive electrode 6 extends in the short side direction from a strip-shaped current collector 6a, a positive electrode active material layer 6b formed on at least one surface of the current collector 6a, and a plurality of long sides of the positive electrode current collector 6a. And a strip-shaped positive electrode current collecting tab 6c. The negative electrode 7 has the same shape as the positive electrode 6, and includes a strip-shaped negative electrode current collector 7 a, a negative electrode active material layer 7 b formed on at least one surface of the negative electrode current collector 7 a, and a long side of the current collector 7 a And a strip-like negative electrode current collecting tab 7c extending in the short side direction. The electrode group wound in a spiral shape is fixed by a stop tape 58.

  The positive and negative electrode current collecting tabs 6c and 7c may be formed by punching a current collector, respectively. The current collector and the current collection tab are formed from, for example, a metal foil. The thickness of the metal foil, that is, the thickness per current collecting tab is desirably 5 μm or more and 50 μm or less. By setting the thickness to 5 μm or more, it is possible to prevent the current collector and the current collection tab from being broken at the time of manufacture and to achieve high current collection efficiency. Moreover, dissolution of the current collecting tab when a large current flows can be avoided. Further, by setting the thickness to 50 μm or less, it is possible to increase the number of circumferences constituting the electrode group while suppressing an increase in the thickness of the electrode group. Preferably, the thickness of the metal foil is not less than 10 μm and not more than 20 μm. Although the material of metal foil can change with the kind of active material used for the positive electrode 6 or the negative electrode 7, aluminum, aluminum alloy, copper, or a copper alloy can be used, for example.

  As shown in FIG. 1, the positive electrode current collecting tab 6 c is curved along the curvature of the electrode group 2, and extends from one end face of the electrode group 2 in a superposed state. The overlapped portion of the positive electrode current collecting tab 6 c is sandwiched between positive electrode protection leads 8. The positive electrode protection lead 8 may have a U shape, a shape bent in two, or a rectangular shape in which the current collecting tab side is opened. Similarly, the negative electrode current collecting tab 7c is curved along the curve of the electrode group 2 and extends from one end face of the electrode group 2 in a superposed state. The overlapped portion of the negative electrode current collecting tab 7 c is sandwiched between the negative electrode protection leads 9. The negative electrode protection lead 9 may be U-shaped, bent into two, or rectangular with the current collecting tab side open.

  For the electrical connection between the positive electrode protection lead 8 and the positive electrode current collection tab 6c and the electrical connection between the negative electrode protection lead 9 and the negative electrode current collection tab 7c, methods such as laser welding, ultrasonic bonding, and resistance welding are used. However, ultrasonic bonding is preferred. The positive and negative electrode protective leads 8 and 9 are preferably made of the same material as the positive and negative current collecting tabs 6c and 7c, respectively. Further, it is desirable that the thickness of the positive and negative electrode protective leads 8 and 9 is larger than three times the thickness of each of the positive and negative electrode current collecting tabs 6c and 7c. A more preferable range is 0.05 mm or more and 0.6 mm or less, and a further preferable range is 0.1 mm or more and 0.5 mm or less.

  The opening of the container 1 is sealed with a sealing member 10. The sealing member 10 includes positive and negative terminals 50 and 5, a gasket 11, a lid 3, positive and negative electrode insulators 53 and 54, positive and negative electrode leads 51 and 52, and positive and negative electrode protection leads 8 and 9. A rectangular recess 15 for accommodating the gasket 11 is provided on the outer surface of the lid 3. The positive electrode terminal 50 is accommodated in one recess 15 and the negative electrode terminal 5 is accommodated in the other recess 15. Each recess 15 is provided with a through hole 16. An electrolyte solution injection port 17 is opened in the lid 3, and is sealed with a sealing lid 18 after the electrolyte solution is injected.

  The positive electrode lead 51 may have a rectangular plate shape having a through hole 51 a as an attachment hole of the shaft portion of the positive electrode terminal 50. The negative electrode lead 52 may have a rectangular plate shape having a through hole 52 a as an attachment hole of the shaft portion of the negative electrode terminal 5. The positive electrode lead 51 and the negative electrode lead 52 are located in the container 1. The positive electrode protection lead 8 holding the tip of the positive electrode current collecting tab 6c is fixed to the positive electrode lead 51 in a state in which electrical connection is maintained. On the other hand, to the negative electrode lead 52, the negative electrode protection lead 9 holding the tip of the negative electrode current collecting tab 7c is fixed in a state where electrical connection is maintained.

  The positive inner insulator 53 may have a rectangular plate shape having a through hole 53 a that communicates with the through hole 16 of the lid 3 and the through hole 51 a of the positive electrode lead 51. The positive inner insulator 53 is disposed between the inner surface of the lid 3 and the positive electrode lead 51 to insulate the lid 3 and the positive electrode lead 51.

  The negative electrode inner insulator 54 is a rectangular plate having a through hole 54 a communicating with the through hole 16 of the lid 3 and the through hole 52 a of the negative electrode lead 52, and a through hole 54 b communicating with the liquid injection port 17 of the lid 3. It may be. The negative inner insulator 54 is disposed between the inner surface of the lid 3 and the negative electrode lead 52 to insulate the lid 3 from the negative electrode lead 52.

  The negative electrode terminal 5 has a rivet shape, and specifically includes a flange portion 5a and a shaft portion 5b extending from the flange portion 5a. The shaft portion 5 b is inserted into the through hole 16 of the lid 3 via the gasket 11, and is also inserted into the through hole 54 a of the internal insulator 54 and the through hole 52 a of the negative electrode lead 52, and is caulked and fixed thereto. On the other hand, the positive electrode terminal 50 has a rivet shape, and specifically includes a flange portion 50a and a shaft portion 50b extending from the flange portion 50a. The shaft portion 50b of the positive electrode terminal 50 is inserted into the through hole 16 of the lid 3 via the gasket 11, and is also inserted into the through hole 53a of the internal insulator 53 and the through hole 51a of the positive electrode lead 51, and is caulked and fixed thereto. ing. Thus, the positive and negative terminals 50 and 5 and the lid 3 are fixed in a state where insulation and airtightness are ensured, and the positive terminal 50 and the positive electrode lead 51 are fixed in a state where electrical connection is ensured. . The negative electrode terminal 5 and the negative electrode lead 52 are also fixed in a state where electrical connection is ensured.

  The lid 3 has a rectangular plate shape, and is seam welded to the opening of the container 1 with, for example, a laser. The lid 3 is made of a metal such as aluminum, aluminum alloy, iron or stainless steel, for example. The lid 3 and the container 1 are preferably formed from the same type of metal.

  The gasket 11 is formed from, for example, polypropylene (PP), thermoplastic fluororesin, or the like. Examples of the thermoplastic fluororesin include tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) and tetrafluoroethylene-hexafluoropropylene copolymer (FEP).

  The positive electrode terminal 50 and the negative electrode terminal 5 are made of, for example, aluminum or an aluminum alloy. In the case of a lithium ion secondary battery using a carbon-based material for the negative electrode active material, the material of the positive electrode terminal is generally aluminum or an aluminum alloy, and the material of the negative electrode terminal is copper, nickel, nickel plated. Metal such as iron is used.

  The positive electrode lead 8 is formed of a conductive material, and the material is changed depending on the type of the positive electrode active material. For example, aluminum or aluminum alloy can be used.

  The negative electrode lead 9 is formed of a conductive material, and the material is changed according to the type of the negative electrode active material. When the negative electrode active material is lithium titanate, aluminum or an aluminum alloy can be used.

  The positive and negative electrode current collecting tabs 6 c and 7 c in FIG. 1 show the shape after being pressure-molded so as to be sandwiched between the positive and negative electrode protection leads 8 and 9. The positive and negative electrode current collecting tabs 6c and 7c before being pressure-formed have a U shape in accordance with the curvature of the wound electrode group 2, and as shown in FIG. And the non-curved portion.

  Here, the curved portion and the non-curved portion of the wound electrode group 2 will be described with reference to FIG. FIG. 4 is a schematic top view of the wound electrode group 2. In the wound electrode group 2, the innermost circumference is defined as one turn from the winding start portion and reaching the winding start portion. Of the length parallel to the long side direction of the wound electrode group 2 on the inner side of the innermost circumference, the maximum length is defined as a non-curved portion length 66. In the wound electrode group 2, a region in the thickness direction whose longitudinal dimension is defined by the non-curved portion length 66 is defined as a non-curved portion 67, and a portion other than the non-curved portion 67, that is, an end face of the wound electrode group 2. Both end portions in the long-side direction are defined as curved portions 65. The non-curved portion length 66 is a length corresponding to the major axis of the core.

  The positive electrode current collecting tab 6 c is located on one curved portion 65, and the negative electrode current collecting tab is located on the other curved portion 65. Further, the positive electrode current collecting tab and the negative electrode current collecting tab are arranged so that both ends parallel to the extending direction are present in the non-curved portion, respectively. Here, both ends parallel to the extending direction of the current collecting tab are referred to as left and right ends for convenience.

  Schematic diagrams of the electrode group as described above are shown in FIGS. As shown in FIG. 5, the length of the current collecting tab in the non-curved portion 67 is preferably the same at the left and right ends. In other words, the left and right ends of the current collecting tab are preferably arranged symmetrically with respect to a reference plane that includes a straight line corresponding to the non-curved portion length 66 and is orthogonal to the thickness direction of the electrode group. Alternatively, as shown in FIG. 6, the left and right ends of the current collecting tab may be disposed asymmetrically with respect to the surface of the non-curved portion length 66. Alternatively, as shown in FIG. 7, one current collecting tab (for example, positive current collecting tab 6c) is disposed asymmetrically with respect to the surface of the non-curved portion length 66, and the other current collecting tab (for example, negative current collecting tab). 7c) may be arranged symmetrically with respect to the surface of the non-curved portion length 66.

  By arranging the positive and negative current collecting tabs 6c and 7c on the curved portion 65 and the non-curved portion 67 of the wound electrode group 2, the tabs are compared with the conventional battery in which the current collecting tab is arranged only on the non-curved portion 67. Can be sufficiently secured in the left-right direction. Moreover, the intensity | strength of current collection tab itself can be improved by making positive / negative electrode current collection tabs 6c and 7c into a U shape. Therefore, damage or breakage of the current collecting tab when an external force such as vibration or impact is applied to the battery can be reduced. According to this embodiment, a battery that is resistant to vibration and excellent in mass productivity can be provided.

  The positive and negative current collecting tabs 6c and 7c are arranged so as not to contact each other in order to prevent an internal short circuit.

  The battery shown in FIG. 1 omits the spacer for convenience of explanation, but may include a spacer for preventing contact between the positive and negative current collecting tabs 6 c and 7 c and the container 1. For example, the first spacer can be disposed on one side and the second spacer can be disposed on the other side with the positive and negative current collecting tabs 6c and 7c on the upper end surface of the electrode group 2 interposed therebetween.

  In the first embodiment, the external terminals of both the positive electrode and the negative electrode are fixed to the lid by caulking, but the negative electrode terminal is fixed to the lid by caulking, and the positive electrode lead is directly welded to the lid. It is good also as an attached structure. Alternatively, the external terminal of the positive electrode may be fixed to the lid by caulking, and the negative electrode lead may be directly attached to the lid by welding. Alternatively, the positive and negative electrode leads and the positive and negative electrode current collecting tabs may be directly connected to each other without the positive and negative electrode leads and the positive and negative electrode protection leads.

  Hereinafter, the positive electrode 6, the negative electrode 7, the separator 59, and the electrolytic solution used in the first embodiment will be described.

  The positive electrode is produced, for example, by applying a slurry containing a positive electrode active material to a current collector. Although it does not specifically limit as a positive electrode active material, The oxide, sulfide, polymer, etc. which can occlude / release lithium can be used. Preferable active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium iron phosphate, and the like that can obtain a high positive electrode potential.

  The negative electrode is produced by applying a slurry containing a negative electrode active material to a current collector. The negative electrode active material is not particularly limited, and metal oxides, metal sulfides, metal nitrides, alloys, carbon, and the like that can occlude and release lithium can be used. It is a substance that becomes noble 0.4 V or more with respect to the metallic lithium potential. Since the negative electrode active material having such a lithium ion storage / release potential can suppress the alloy reaction between aluminum or an aluminum alloy and lithium, it is possible to use aluminum or an aluminum alloy for a negative electrode current collector and a negative electrode related component. And For example, there are titanium oxide, lithium titanium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, etc. Among them, lithium titanium composite oxide is preferable.

  As the separator, a microporous film, a woven fabric, a non-woven fabric, a laminate of the same material or different materials among these can be used. Examples of the material for forming the separator include polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-butene copolymer.

  As the electrolytic solution, a nonaqueous electrolytic solution prepared by dissolving an electrolyte (for example, lithium salt) in a nonaqueous solvent is used. Examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone (γ -BL), sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran and the like. Nonaqueous solvents may be used alone or in combination of two or more.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), and trifluorometa. A lithium salt such as lithium sulfonate (LiCF ₃ SO ₃ ) can be given. The electrolyte may be used alone or in combination of two or more. The amount of electrolyte dissolved in the non-aqueous solvent is desirably 0.2 mol / L to 3 mol / L.

(Second Embodiment)
As a second embodiment, a non-aqueous electrolyte battery that is excellent in mass productivity with little misalignment of tabs will be described. According to such an embodiment, when the current collecting tab is laminated in the thickness direction of the electrode group 2 at a predetermined position as described in the first embodiment, the tab misalignment can be reduced. .

An example of the positive electrode and the negative electrode used in the second embodiment is shown in FIG. As shown in FIG. 8, the positive electrode 6 (negative electrode 7) includes a positive electrode current collector (negative electrode current collector) and a plurality of strip-like positive electrode current collector tabs 6c ₁ extending from the positive electrode current collector (negative electrode current collector). To 6c ₆ (negative electrode current collecting tabs 7c _{1 to} 7c ₆ ) and a positive electrode active material-containing layer 6b (negative electrode active material-containing layer 7b) formed on both surfaces of the positive electrode current collector (negative electrode current collector). . The distance d ₁ to d ₅ between the negative electrode current collector tab 7c ₁ ~7c ₆ at a distance d ₁ to d ₅ and the negative electrode 7 between the positive electrode current collector tabs 6c ₁ ~6c ₆ in the positive electrode 6, the inner peripheral side of the electrode group 2 It increases toward the outer peripheral side, and is expressed by the following formula (1).

2nπd (1)
However, n is equal to the positive electrode current collecting tab position counted from the inner peripheral side of the electrode group 2 or the negative electrode current collecting tab position counted from the inner peripheral side of the electrode group 2. In other words, of the positive electrode (negative electrode) tabs at both ends that define the distance, the position of the positive electrode (negative electrode) tab located on the outer peripheral side of the electrode group is n. d is the sum of the thickness of the positive electrode 6, the thickness of the negative electrode 7, and the thickness of the separator, and π is the circumference. The thicknesses of the positive electrode 6, the negative electrode 7, and the separator are measured with an upright gauge.

For example, the positive electrode current collector tab 6c ₁ is positioned at the beginning of winding of the positive electrode 1, and the distance between the positive electrode current collector tab 6c ₁ and the positive electrode current collector tab 6c ₂ is d ₁ . The distance d ₁ is represented by 4πd because n is 2. The distance d ₂ between the positive electrode current collector tab 6c ₂ and the positive electrode current collector tab 6c ₃ is represented by 6πd because n is 3. The distance d ₃ between the positive electrode current collecting tab 6c ₃ and the positive electrode current collecting tab 6c ₄ is represented by 8πd because n is 4. Further, the distance d ₄ between the positive current collecting tab 6c ₄ and the positive current collecting tab 6c ₅ is expressed by 10πd because n is 5. Further, the distance d ₅ between the positive electrode current collecting tab 6c ₅ and the positive electrode current collecting tab 6c ₆ is represented by 12πd because n is 6. The same applies to the negative electrode 7.

After the separator is interposed between the positive electrode and the negative electrode having the configuration shown in FIG. 8 and wound in a spiral shape, a flat shape is formed by pressing to obtain an electrode group 2 as shown in FIG. The positive electrode current collecting tabs 6c _{1 to} 6c ₆ and the negative electrode current collecting tabs 7c _{1 to} 7c ₆ are projected from the end surface on one side of the electrode, and the positions of the positive electrode current collecting tabs 6c _{1 to} 6c ₆ and the negative electrode current collecting tabs 7c _{1 to} 7c Can align with ₆ position. As a result, the mass productivity of the nonaqueous electrolyte battery capable of realizing rapid charging and high output discharge is improved. Further, even if the number of circumferences of the electrode group is increased, it is possible to eliminate a problem in the thickness of the electrode group.

  The distance between the positive electrode current collecting tabs and the distance between the negative electrode current collecting tabs are desirably 300 mm or less.

  The widths of the positive electrode current collecting tab and the negative electrode current collecting tab are arbitrarily determined depending on the capacity and shape of the battery to be produced, but are usually preferably 5 mm to 300 mm. By setting the width to 5 mm or more, it is possible to suppress an increase in resistance at the tab portion when a large current flows to increase current collection efficiency and to suppress dissolution of the tab.

  Hereinafter, embodiments of the present invention will be described in detail.

Example 1
Positive and negative electrode current collecting tabs were arranged as shown in FIG. 5 to produce a wound electrode group, and a non-aqueous electrolyte secondary battery was produced using this.

  A coating liquid mainly composed of lithium cobaltate was prepared. The prepared coating solution was applied to both sides of an aluminum foil (thickness: 15 μm) as a positive electrode current collector and dried to produce a positive electrode.

  A coating liquid mainly composed of lithium titanate was prepared. The prepared coating solution was applied to both sides of an aluminum foil (thickness 15 μm) as a negative electrode current collector and dried to produce a negative electrode.

  About each of the produced positive electrode and negative electrode, it punched 40 times with the press which set the type | mold designed so that a current collection tab could be shape | molded. At this time, punching was performed while increasing the amount of movement of the positive and negative electrodes by a value represented by 2πd. The punched positive and negative electrodes were pressed to a predetermined density by a roller press to obtain a positive electrode and a negative electrode. In each of the positive electrode and the negative electrode, the distance between the current collecting tabs increases by a pitch amount (Δ) represented by 2πd from the inner peripheral side to the outer peripheral side of the electrode group. As the separator, a resin separator having a thickness of 30 μm was prepared. The thickness of the positive electrode was 150 μm, and the thickness of the negative electrode was 180 μm. The width of the positive and negative current collecting tabs was 40 mm.

  A cylindrical wound electrode group was fabricated by winding a separator between the positive electrode and the negative electrode for 40 turns. Next, this was heated and pressed at about 80 ° C. to form a flat shape and fixed with an insulating tape to produce a flat wound electrode group. In Example 1, the positive electrode and the negative electrode current collecting tabs were wound so that the left and right ends of the current collecting tabs were symmetrical in the non-curved portion, which were positioned in the curved portion and the non-curved portion of the electrode group. The thickness of the electrode group was about 28.8 mm.

  The positive and negative electrode current collecting tabs were fixed to the positive and negative electrode leads of the sealing member with the positive and negative electrode terminals by laser welding. The electrode group with positive and negative electrode leads was inserted into the outer can, and the lid and the outer can were laser welded to seal the outer can. A non-aqueous electrolyte was injected from the inlet opened in the lid, a sealing plug was inserted, and sealing was performed by laser welding to produce a non-aqueous electrolyte secondary battery.

(Example 2)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive and negative electrode current collecting tabs were arranged as shown in FIG. In the electrode group of Example 2, the positive and negative electrode current collecting tabs are positioned at the curved and non-curved portions of the electrode group, and the left and right ends of the current collecting tabs are asymmetric at the non-curved portion. Has been. The width of the positive and negative current collecting tabs was 60 mm.

(Example 3)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive and negative electrode current collecting tabs were arranged as shown in FIG. In the electrode group of Example 3, the negative electrode current collecting tabs are arranged so that the left and right ends are symmetric in the non-curved portion as in Example 1. On the other hand, the positive electrode current collecting tab is arranged so that the left and right ends are asymmetric in the non-curved portion, as in the second embodiment. The width of the positive electrode current collecting tab was 60 mm, and the width of the negative electrode current collecting tab was 40 mm.

(Comparative Example 1)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive and negative electrode current collecting tabs were arranged as shown in FIG. In the electrode group of Comparative Example 1, one end of the positive electrode and the negative electrode current collecting tab is located in the non-curved portion, but the other end is located in the curved portion so that the entire portion hardly bends. Has been placed. The width of the positive and negative current collecting tabs was 15 mm.

(Comparative Example 2)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive and negative electrode current collecting tabs were arranged as shown in FIG. In the electrode group of Comparative Example 2, one end of the positive and negative current collecting tabs is located in the non-curved part, but the other end is located in the curved part. The end portion located in the bending portion is arranged so that a part thereof is bent. The width of the positive and negative current collecting tabs was 20 mm.

(Comparative Example 3)
A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the positive and negative electrode current collecting tabs were arranged as shown in FIG. In the electrode group of Comparative Example 2, both ends of the positive electrode and the negative electrode current collecting tab are located in the curved portion instead of the non-curved portion. The width of the positive and negative current collecting tabs was 15 mm.

(Vibration test)
Five batteries of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared, and the vibration test described in the UN test (guidance on transport of lithium batteries and lithium ion batteries) was performed. The results are shown in Table 1 below.

  In the batteries of Examples 1 to 3, the positive and negative electrode current collecting tabs did not break. On the other hand, in the batteries of Comparative Examples 1 to 3, the positive and negative electrode current collecting tabs were broken. The batteries of Comparative Examples 1 and 2 have low tensile strength because the positive and negative electrode current collecting tabs are not U-shaped, and as a result, it is considered that breakage occurred. In the battery of Comparative Example 3, although the positive and negative electrode current collecting tabs have a shape close to a U-shape, it is considered that the strength is low because the length in the left-right direction is insufficient.

  As described above, according to the embodiment of the present invention, it is possible to provide a good secondary battery in which the current collecting tab is not broken by an impact or the like.

  In the above-described embodiments, the battery using the non-aqueous electrolyte is described as an example, but the present invention can naturally be applied to a battery using a solid electrolyte or a polymer electrolyte instead of the non-aqueous electrolyte. Furthermore, the positive and negative electrode active materials are not limited to this, and other active materials can be used.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Container, 2 ... Electrode group, 3 ... Cover, 5 ... Negative electrode terminal, 6 ... Positive electrode, 6a ... Positive electrode collector, 6b ... Positive electrode active material layer, 6c ... Positive electrode current collection tab, 7 ... Negative electrode, 7a ... Negative electrode Current collector, 7b ... negative electrode active material layer, 7c ... negative electrode current collecting tab, 8 ... positive electrode protective lead, 9 ... negative electrode protective lead, 10 ... sealing member, 50 ... positive electrode terminal, 51 ... positive electrode lead, 52 ... negative electrode lead, 53, 54 ... Insulator, 58 ... Stopping tape, 59 ... Separator, 65 ... Curved part, 66 ... Non-curved part length, 67 ... Non-curved part.

Claims (8)

A container,
An electrode group housed in the container, including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and wound in a flat spiral shape;
A plurality of positive electrode current collector tabs extending from a plurality of locations on one end face of the positive electrode current collector of the positive electrode;
A plurality of negative electrode current collector tabs extending from a plurality of locations on one end face of the negative electrode current collector of the negative electrode;
A lid that closes the opening of the container;
A positive terminal provided on the lid and electrically connected to the positive current collecting tab;
A negative electrode terminal provided on the lid and electrically connected to the negative electrode current collecting tab;
The electrode group has a curved portion occupying both ends in the long side direction on an end surface thereof and a non-curved portion sandwiched between the curved portions, and the positive electrode current collecting tab is located on one of the curved portions, and the negative electrode A current collecting tab is located on the other curved portion, and further, both ends of the positive current collecting tab and the negative current collecting tab parallel to the extending direction are located on the non-curved portion, respectively. .   The battery according to claim 1, wherein the positive current collecting tab and the negative current collecting tab do not contact each other.   The both ends parallel to the extending direction of at least one of the positive electrode current collecting tab and the negative electrode current collecting tab are arranged symmetrically in the non-curved portion. battery. The distance between the said positive electrode current collection tabs in the said positive electrode and the distance between the said negative electrode current collection tabs in the said negative electrode are respectively represented by following (1) Formula, The any one of Claims 1-3 characterized by the above-mentioned. Battery described in the section:
2nπd (1)
However,
n is the position of the positive electrode current collecting tab or the position of the negative electrode current collecting tab counted from the inner peripheral side of the electrode group;
d is the sum of the thickness of the positive electrode, the thickness of the negative electrode, and twice the thickness of the separator;
π is the circumference ratio.   5. The battery according to claim 1, wherein thicknesses of the positive electrode current collecting tab and the negative electrode current collecting tab are in a range of 5 μm to 50 μm.   The number of the said positive electrode current collection tab and the said negative electrode current collection tab is the same as the number of times of the said electrode group, The nonaqueous electrolyte battery as described in any one of Claims 1-5 characterized by the above-mentioned.   The battery according to any one of claims 1 to 6, wherein at least one of the positive electrode current collecting tab and the negative electrode current collecting tab is made of aluminum or an aluminum alloy.   The nonaqueous electrolyte battery according to any one of claims 1 to 7, wherein at least one of the positive electrode current collecting tab and the negative electrode current collecting tab is made of copper or a copper alloy.

Images